[HTC Wildfire S] Olivier:
Ok guys, I've found out which script has been used in the Sense 4 ROM for the Explorer (A310e).

Here it is, I'm sure it'll help (attached it as well).

#!/system/bin/sh
#
##############SUPER SD-EXT SCRIPT BY DEREFAS##########
# Linking app_s,media_s and usr_s to system
mount -o remount,rw /system
if [ ! -d "/system/app" ];
then
mkdir /system/app
chmod 755 /system/app
chown root.root /system/app
fi;
chmod 755 /sd-ext/app_s
chown root.root /sd-ext/app_s
mount -o bind /sd-ext/app_s /system/app
#if we use old script we should ln dat from sd-ext
if [ ! -d "/system/media" ];
then
ln -s /sd-ext/media_s /system/media
fi;
if [ ! -d "/system/usr" ];
then
ln -s /sd-ext/usr_s /system/usr
fi;
# Moving stuff from sd-ext to data , and linking from data to sd-ext to
# inrease speed and stability
# Dalvik-cache will move to data only after second boot, it means after # # 1st rom boot you need to reboot you phone to move dalvik to data
#
# Dalivk cache
if [ ! -d "/data/dalvik-cache" ];
then
mkdir /data/dalvik-cache
chown system.system /data/dalvik-cache
chmod 0771 /data/dalvik-cache
fi;
if [ ! -d "/sd-ext/dalvik-cache" ];
then
mkdir /sd-ext/dalvik-cache
chown system.system /sd-ext/dalvik-cache
chmod 0771 /sd-ext/dalvik-cache
fi;
mount -o bind /sd-ext/dalvik-cache /data/dalvik-cache
#app folder
if [ ! -d "/data/app" ];
then
mkdir /data/app
chown system.system /data/app
chmod 0771 /data/app
fi;
if [ ! -d "/sd-ext/app" ];
then
mkdir /sd-ext/app
chown system.system /sd-ext/app
chmod 0771 /sd-ext/app
fi;
mount -o bind /sd-ext/app /data/app
#/data folder
#if [ ! -d "/data/data" ];
#then
#mkdir /data/data
#chown system.system /data/data
#chmod 0771 /data/data
#fi;
#if [ ! -d "/sd-ext/data" ];
#then
#mkdir /sd-ext/data
#chown system.system /sd-ext/data
#chmod 0771 /sd-ext/data
#fi;
#mount -o bind /sd-ext/data /data/data

Some pics of the ROM:

Plus the updater-script:

ui_print("Installing HTC Sense 4.0 Build 8");
ui_print("Codename Revolt");

ui_print("Mounting sd-ext");
ui_print("------------------");
run_program("/sbin/mkdir", "/sd-ext");
run_program("/sbin/busybox", "mount", "-t", "auto", "/dev/block/mmcblk0p2", "/sd-ext");

ui_print("Mounting data");
ui_print("------------------");

run_program("/sbin/mkdir", "/data");
mount("yaffs2", "MTD","userdata","/data");
set_progress(0.01);

ui_print("Formating data");
ui_print("------------------");

format("yaffs2", "MTD", "userdata");
set_progress(0.02);

ui_print("Cleaning /sd-ext");
ui_print("------------------");

run_program("/sbin/busybox", "rm", "-rf", "/sd-ext/*");
run_program("/sbin/busybox", "rm", "-rf", "/sdcard/.android_secure/*");
set_progress(0.05);

ui_print("Formatting system");
ui_print("------------------");

format("yaffs2", "MTD", "system");
set_progress(0.10);

ui_print("Mounting system");
ui_print("------------------");

run_program("/sbin/mkdir", "/system");
mount("yaffs2", "MTD", "system", "/system");
set_progress(0.15);

ui_print("Installing system files");
ui_print("------------------");

package_extract_dir("system", "/system");
set_progress(0.20);

ui_print("Flashing boot.img");
ui_print("------------------");

assert(package_extract_file("boot.img", "/tmp/boot.img"),
write_raw_image("/tmp/boot.img", "boot"),
delete("/tmp/boot.img"));
set_progress(0.22);

ui_print("Preparing sd-ext for flashing");
ui_print("------------------");

run_program("/sbin/mkdir","/sd-ext/app_s");
run_program("/sbin/mkdir","/sd-ext/system_s");
run_program("/sbin/mkdir","/sd-ext/usr_s");
run_program("/sbin/mkdir","/sd-ext/media_s");
set_progress(0.25);

ui_print("Flashing stuff to sd-ext");
ui_print("------------------");

package_extract_dir("sd-ext/app_s", "/sd-ext/app_s");
package_extract_dir("sd-ext/media_s", "/sd-ext/media_s");
package_extract_dir("sd-ext/usr_s", "/sd-ext/usr_s");
package_extract_dir("sd-ext/system_s", "/sd-ext/system_s");
set_perm_recursive(0, 0, 0755, 0644, "/sd-ext/app_s");
set_perm_recursive(0, 0, 0755, 0644, "/sd-ext/media_s");
set_perm_recursive(0, 0, 0755, 0644, "/sd-ext/usr_s");
set_perm_recursive(0, 0, 0755, 0644, "/sd-ext/system_s");
package_extract_dir("bootanimation", "/sd-ext/media_s");
set_progress(0.30);

ui_print("Symlinking toolbox");
ui_print("------------------");

symlink("dumpstate", "/system/bin/dumpcrash");
symlink("toolbox", "/system/bin/cat");
symlink("toolbox", "/system/bin/chmod");
symlink("toolbox", "/system/bin/chown");
symlink("toolbox", "/system/bin/cmp");
symlink("debuggerd", "/system/bin/csview");
symlink("toolbox", "/system/bin/date");
symlink("toolbox", "/system/bin/dd");
symlink("toolbox", "/system/bin/df");
symlink("toolbox", "/system/bin/dmesg");
symlink("toolbox", "/system/bin/getevent");
symlink("toolbox", "/system/bin/getprop");
symlink("toolbox", "/system/bin/hd");
symlink("toolbox", "/system/bin/id");
symlink("toolbox", "/system/bin/ifconfig");
symlink("toolbox", "/system/bin/iftop");
symlink("toolbox", "/system/bin/insmod");
symlink("toolbox", "/system/bin/ioctl");
symlink("toolbox", "/system/bin/ionice");
symlink("toolbox", "/system/bin/kill");
symlink("toolbox", "/system/bin/ln");
symlink("toolbox", "/system/bin/log");
symlink("toolbox", "/system/bin/ls");
symlink("toolbox", "/system/bin/lsmod");
symlink("toolbox", "/system/bin/lsof");
symlink("toolbox", "/system/bin/mkdir");
symlink("toolbox", "/system/bin/mount");
symlink("toolbox", "/system/bin/mv");
symlink("toolbox", "/system/bin/nandread");
symlink("toolbox", "/system/bin/netstat");
symlink("toolbox", "/system/bin/newfs_msdos");
symlink("toolbox", "/system/bin/notify");
symlink("toolbox", "/system/bin/printenv");
symlink("toolbox", "/system/bin/ps");
symlink("toolbox", "/system/bin/renice");
symlink("toolbox", "/system/bin/rm");
symlink("toolbox", "/system/bin/rmdir");
symlink("toolbox", "/system/bin/rmmod");
symlink("toolbox", "/system/bin/route");
symlink("toolbox", "/system/bin/schedtop");
symlink("toolbox", "/system/bin/sendevent");
symlink("toolbox", "/system/bin/setconsole");
symlink("toolbox", "/system/bin/setprop");
symlink("mksh", "/system/bin/sh");
symlink("toolbox", "/system/bin/sleep");
symlink("toolbox", "/system/bin/smd");
symlink("toolbox", "/system/bin/start");
symlink("toolbox", "/system/bin/stop");
symlink("toolbox", "/system/bin/sync");
symlink("toolbox", "/system/bin/top");
symlink("toolbox", "/system/bin/touch");
symlink("toolbox", "/system/bin/umount");
symlink("toolbox", "/system/bin/uptime");
symlink("toolbox", "/system/bin/vmstat");
symlink("toolbox", "/system/bin/watchprops");
symlink("toolbox", "/system/bin/wipe");
set_progress(0.40);

ui_print("Setting permissions");
ui_print("------------------");

set_perm_recursive(0, 0, 0755, 0644, "/system");
#binaries
set_perm_recursive(0, 2000, 0755, 0755, "/system/bin");
set_perm(0, 3003, 06755, "/system/bin/ip");
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(0, 1000, 04750, "/system/bin/iptables");
set_perm(0, 1000, 04750, "/system/bin/tc");
set_perm(1000, 1000, 0755, "/system/bin/sysro");
set_perm(1000, 1000, 0755, "/system/bin/sysrw");
#bluetooth
set_perm_recursive(1002, 1002, 0755, 0440, "/system/etc/bluetooth");
set_perm(0, 0, 0755, "/system/etc/bluetooth");
set_perm(0, 0, 0644, "/system/etc/bluetooth/a2dp_avrcp.conf");
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_recursive(0, 0, 0755, 0555, "/system/etc/ppp");
set_perm_recursive(0, 2000, 0755, 0644, "/system/vendor");
set_perm_recursive(0, 0, 0755, 0644, "/system/vendor/firmware");
set_perm(0, 2000, 0755, "/system/vendor/firmware");
#Fonts
symlink("Roboto-Bold.ttf", "/system/fonts/DroidSans-Bold.ttf");
symlink("Roboto-Regular.ttf", "/system/fonts/DroidSans.ttf");
#Xbin
set_perm_recursive(0, 2000, 0755, 0755, "/system/xbin");
set_perm(0, 0, 06755, "/system/xbin/su");
set_perm(1000, 1000, 0755, "/system/xbin/openvpn");
set_perm(0, 1000, 0755, "/system/xbin/busybox");
symlink("/system/xbin/busybox", "/system/bin/busybox");
set_perm(0, 0, 04755, "/system/xbin/sysrw");
set_perm(0, 0, 04755, "/system/xbin/sysro");

set_progress(0.85);

ui_print("Installing SuperUser..");
ui_print("------------------");

set_perm(0, 0, 06755, "/system/bin/su");
symlink("/system/bin/su", "/system/xbin/su");
set_progress(0.90);

ui_print("Installing Busybox..");
ui_print("------------------");

package_extract_file("additions/installbusybox", "/tmp/installbusybox");
set_progress(0.95);

set_perm(0, 0, 0777, "/tmp/installbusybox");
run_program("/tmp/installbusybox");
run_program("/sbin/busybox", "umount", "/data");
run_program("/sbin/busybox", "umount", "/sd-ext");
run_program("/sbin/busybox", "umount", "/system");
set_progress(0.1);
show_progress(0.100000, 0);
ui_print("Done!");