[Sony Ericsson Xperia Mini, Mini Pro, Xperia Pro, A] karandpr:
I was pretty much right ....

Format system

format("ext4", "EMMC", "/dev/block/stl12");

Mount system

mount("ext4", "EMMC", "/dev/block/stl12", "/system");
mount("ext4", "EMMC", "/dev/block/stl13", "/data");

Install Rom

package_extract_dir("recovery", "/system");
package_extract_dir("system", "/system");
package_extract_dir("data", "/data");

Symlink and Fix permissions /Misc actions

symlink("busybox", "/system/xbin/[", "/system/xbin/[[",
"/system/xbin/adjtimex", "/system/xbin/arp", "/system/xbin/ash",
"/system/xbin/awk", "/system/xbin/base64", "/system/xbin/basename",
"/system/xbin/bbconfig", "/system/xbin/blkid", "/system/xbin/blockdev",
"/system/xbin/brctl", "/system/xbin/bunzip2", "/system/xbin/bzcat",
"/system/xbin/bzip2", "/system/xbin/cal", "/system/xbin/cat",
"/system/xbin/catv", "/system/xbin/chattr", "/system/xbin/chgrp",
"/system/xbin/chmod", "/system/xbin/chown", "/system/xbin/chroot",
"/system/xbin/clear", "/system/xbin/cmp", "/system/xbin/comm",
"/system/xbin/cp", "/system/xbin/cpio", "/system/xbin/crond",
"/system/xbin/crontab", "/system/xbin/cut", "/system/xbin/date",
"/system/xbin/dc", "/system/xbin/dd", "/system/xbin/depmod",
"/system/xbin/devmem", "/system/xbin/df", "/system/xbin/diff",
"/system/xbin/dirname", "/system/xbin/dmesg", "/system/xbin/dnsd",
"/system/xbin/dos2unix", "/system/xbin/du", "/system/xbin/echo",
"/system/xbin/ed", "/system/xbin/egrep", "/system/xbin/env",
"/system/xbin/expand", "/system/xbin/expr", "/system/xbin/false",
"/system/xbin/fbsplash", "/system/xbin/fdisk", "/system/xbin/fgrep",
"/system/xbin/find", "/system/xbin/flash_lock",
"/system/xbin/flash_unlock", "/system/xbin/flashcp",
"/system/xbin/flock", "/system/xbin/fold", "/system/xbin/free",
"/system/xbin/freeramdisk", "/system/xbin/fsync", "/system/xbin/ftpget",
"/system/xbin/ftpput", "/system/xbin/fuser", "/system/xbin/getopt",
"/system/xbin/grep", "/system/xbin/groups", "/system/xbin/gunzip",
"/system/xbin/gzip", "/system/xbin/halt", "/system/xbin/head",
"/system/xbin/hexdump", "/system/xbin/id", "/system/xbin/ifconfig",
"/system/xbin/inetd", "/system/xbin/insmod", "/system/xbin/install",
"/system/xbin/ionice", "/system/xbin/iostat", "/system/xbin/ip",
"/system/xbin/kill", "/system/xbin/killall", "/system/xbin/killall5",
"/system/xbin/less", "/system/xbin/ln", "/system/xbin/losetup",
"/system/xbin/ls", "/system/xbin/lsattr", "/system/xbin/lsmod",
"/system/xbin/lsusb", "/system/xbin/lzcat", "/system/xbin/lzma",
"/system/xbin/lzop", "/system/xbin/lzopcat", "/system/xbin/man",
"/system/xbin/md5sum", "/system/xbin/mesg", "/system/xbin/mkdir",
"/system/xbin/mke2fs", "/system/xbin/mkfifo", "/system/xbin/mkfs.ext2",
"/system/xbin/mkfs.vfat", "/system/xbin/mknod", "/system/xbin/mkswap",
"/system/xbin/mktemp", "/system/xbin/modinfo", "/system/xbin/modprobe",
"/system/xbin/more", "/system/xbin/mount", "/system/xbin/mountpoint",
"/system/xbin/mpstat", "/system/xbin/mv", "/system/xbin/nanddump",
"/system/xbin/nandwrite", "/system/xbin/nbd-client",
"/system/xbin/netstat", "/system/xbin/nice", "/system/xbin/nohup",
"/system/xbin/nslookup", "/system/xbin/ntpd", "/system/xbin/od",
"/system/xbin/patch", "/system/xbin/pgrep", "/system/xbin/pidof",
"/system/xbin/ping", "/system/xbin/pipe_progress", "/system/xbin/pkill",
"/system/xbin/pmap", "/system/xbin/poweroff", "/system/xbin/printenv",
"/system/xbin/printf", "/system/xbin/ps", "/system/xbin/pstree",
"/system/xbin/pwd", "/system/xbin/pwdx", "/system/xbin/rdev",
"/system/xbin/readlink", "/system/xbin/realpath", "/system/xbin/renice",
"/system/xbin/reset", "/system/xbin/resize", "/system/xbin/rev",
"/system/xbin/rm", "/system/xbin/rmdir", "/system/xbin/rmmod",
"/system/xbin/route", "/system/xbin/run-parts", "/system/xbin/rx",
"/system/xbin/sed", "/system/xbin/seq", "/system/xbin/setconsole",
"/system/xbin/setserial", "/system/xbin/setsid", "/system/xbin/sh",
"/system/xbin/sha1sum", "/system/xbin/sha256sum",
"/system/xbin/sha3sum", "/system/xbin/sha512sum", "/system/xbin/sleep",
"/system/xbin/sort", "/system/xbin/split", "/system/xbin/stat",
"/system/xbin/strings", "/system/xbin/stty", "/system/xbin/sum",
"/system/xbin/swapoff", "/system/xbin/swapon", "/system/xbin/sync",
"/system/xbin/sysctl", "/system/xbin/tac", "/system/xbin/tail",
"/system/xbin/tar", "/system/xbin/tee", "/system/xbin/telnet",
"/system/xbin/telnetd", "/system/xbin/test", "/system/xbin/tftp",
"/system/xbin/tftpd", "/system/xbin/time", "/system/xbin/timeout",
"/system/xbin/top", "/system/xbin/touch", "/system/xbin/tr",
"/system/xbin/traceroute", "/system/xbin/true", "/system/xbin/ttysize",
"/system/xbin/tune2fs", "/system/xbin/umount", "/system/xbin/uname",
"/system/xbin/uncompress", "/system/xbin/unexpand", "/system/xbin/uniq",
"/system/xbin/unix2dos", "/system/xbin/unlzma", "/system/xbin/unlzop",
"/system/xbin/unxz", "/system/xbin/unzip", "/system/xbin/uptime",
"/system/xbin/usleep", "/system/xbin/uudecode", "/system/xbin/uuencode",
"/system/xbin/vi", "/system/xbin/watch", "/system/xbin/wc",
"/system/xbin/wget", "/system/xbin/which", "/system/xbin/whoami",
"/system/xbin/xargs", "/system/xbin/xz", "/system/xbin/xzcat",
"/system/xbin/yes",
"/system/xbin/zcat");
symlink("toolbox", "/system/bin/cat", "/system/bin/cmp",
"/system/bin/date", "/system/bin/dd", "/system/bin/getevent",
"/system/bin/getprop", "/system/bin/hd", "/system/bin/id",
"/system/bin/ifconfig", "/system/bin/iftop", "/system/bin/insmod",
"/system/bin/ioctl", "/system/bin/ionice", "/system/bin/kill",
"/system/bin/log", "/system/bin/lsmod", "/system/bin/nandread",
"/system/bin/netstat", "/system/bin/newfs_msdos", "/system/bin/notify",
"/system/bin/printenv", "/system/bin/ps", "/system/bin/reboot",
"/system/bin/renice", "/system/bin/rmdir", "/system/bin/rmmod",
"/system/bin/route", "/system/bin/schedtop", "/system/bin/sendevent",
"/system/bin/setconsole", "/system/bin/setprop", "/system/bin/sleep",
"/system/bin/smd", "/system/bin/start", "/system/bin/stop",
"/system/bin/sync", "/system/bin/top", "/system/bin/uptime",
"/system/bin/vmstat", "/system/bin/watchprops",
"/system/bin/wipe");
set_perm_recursive(0, 0, 0755, 0644, "/system");
set_perm_recursive(0, 2000, 0755, 0755, "/system/bin");
set_perm(0, 3003, 02750, "/system/bin/netcfg");
set_perm(0, 3004, 02755, "/system/bin/ping");
set_perm(0, 2000, 06750, "/system/bin/run-as");
set_perm(1000, 1003, 02755, "/system/bin/screenshot");
set_perm_recursive(1002, 1002, 0755, 0440, "/system/etc/bluetooth");
set_perm(0, 0, 0755, "/system/etc/bluetooth");
set_perm(1000, 1000, 0640, "/system/etc/bluetooth/auto_pairing.conf");
set_perm(3002, 3002, 0444, "/system/etc/bluetooth/blacklist.conf");
set_perm(1002, 1002, 0440, "/system/etc/dbus.conf");
set_perm(1014, 2000, 0550, "/system/etc/dhcpcd/dhcpcd-run-hooks");
set_perm_recursive(0, 2000, 0755, 0750, "/system/etc/init.d");
set_perm(0, 0, 0755, "/system/etc/init.d");
set_perm(0, 2000, 0550, "/system/etc/init.goldfish.sh");
set_perm(0, 0, 0544, "/system/etc/install-recovery.sh");
set_perm_recursive(0, 0, 0755, 0555, "/system/etc/ppp");
set_perm_recursive(0, 2000, 0755, 0755, "/system/xbin");
set_perm(0, 0, 06755, "/system/xbin/hcitool");
set_perm(0, 0, 06755, "/system/xbin/librank");
set_perm(0, 0, 06755, "/system/xbin/procmem");
set_perm(0, 0, 06755, "/system/xbin/procrank");
set_perm(0, 0, 06755, "/system/xbin/su");
set_perm(0, 0, 06755, "/system/xbin/tcpdump");
set_perm_recursive(0, 2000, 0755, 0755, "/system/holder");
set_perm(0, 0, 0755, "/system/holder");
set_perm(0, 0, 0755, "/system/holder/40int2ext");
set_perm_recursive(0, 2000, 0777, 0777, "/system/etc/init.d");
set_perm_recursive(0, 2000, 0777, 0777, "/system/usr/idc");
set_perm(0, 0, 0777, "/system/etc/init.d/40int2ext");
set_perm(0, 0, 0777, "/system/bin/boost");
set_perm(0, 0, 0777, "/system/xbin/sqlite3");
set_perm(0, 0, 0777, "/system/xbin/zipalign");
set_perm(0, 0, 0777, "/system/xbin/openvpn");
set_perm(0, 0, 0777, "/system/lib/libncurses.so");
set_perm(0, 0, 0777, "/system/lib/libsqlite.so");
set_perm(0, 0, 0777, "/system/lib/libsqlite_jni.so");
set_perm(0, 0, 0777, "/system/etc/init.d/S98system_tweak");
set_perm(0, 0, 0777, "/system/etc/init.d/S70darky_zipalign");
set_perm(0, 0, 0777, "/system/etc/init.d/sqlite_optimize");
set_perm(0, 0, 0777, "/system/etc/init.d/ram_optimize");
set_perm(0, 0, 0777, "/system/etc/init.d/ext4_lagfix");
set_perm(0, 0, 0777, "/data/local.prop");
set_perm(0, 0, 0777, "/system/usr/idc/mxt244_ts_input.idc");
set_perm_recursive(1000, 1000, 0771, 0644, "/data/app");
show_progress(0.200000, 0);
show_progress(0.200000, 10);
package_extract_file("system/bin/backuptool.sh", "/tmp/backuptool.sh");
set_perm(0, 0, 0777, "/tmp/backuptool.sh");
run_program("/tmp/backuptool.sh", "restore");
package_extract_file("system/bin/modelid_cfg.sh", "/tmp/modelid_cfg.sh");
set_perm(0, 0, 0777, "/tmp/modelid_cfg.sh");
run_program("/tmp/modelid_cfg.sh");
package_extract_file("system/bin/verify_cache_partition_size.sh", "/tmp/verify_cache_partition_size.sh");
set_perm(0, 0, 0777, "/tmp/verify_cache_partition_size.sh");
run_program("/tmp/verify_cache_partition_size.sh");
show_progress(0.200000, 10);

Flash kernel

assert(package_extract_file("boot.img", "/tmp/boot.img"),
write_raw_image("/tmp/boot.img", "boot"),
delete("/tmp/boot.img"));

Unmount system

unmount("/system");

Updater scripts are pretty much black and white ...No chance / use of modification ...

Disclaimer : if some genius reads this and attempts to flash a kernel using the code in updater script on an Xperia device . DONT . Samsung devices have two kernel partitions ,one for recovery and one for boot .

Xperia devices use one kernel with two ramdisks ....

Attempting to use this script will perma brick the device or wont do anything if you are lucky...