[Nexus S General] greenblue:
I think he means something like this:

--- a/device/samsung/crespo4g/init.herring.rc
+++ b/device/samsung/crespo4g/init.herring.rc
@@ -1,5 +1,20 @@
import init.herring.usb.rc

+on init
+ # See storage config details at http://source.android.com/tech/storage/
+ mkdir /mnt/shell/emulated 0700 shell shell
+ mkdir /storage/emulated 0555 root root
+
+ export EXTERNAL_STORAGE /storage/emulated/legacy
+ export EMULATED_STORAGE_SOURCE /mnt/shell/emulated
+ export EMULATED_STORAGE_TARGET /storage/emulated
+
+ # Support legacy paths
+ symlink /storage/emulated/legacy /sdcard
+ symlink /storage/emulated/legacy /mnt/sdcard
+ symlink /storage/emulated/legacy /storage/sdcard0
+ symlink /mnt/shell/emulated/0 /storage/emulated/legacy
+
on boot
mount debugfs /sys/kernel/debug /sys/kernel/debug

@@ -41,12 +56,6 @@
chmod 770 /efs/imei
mount_all /fstab.herring

- export EXTERNAL_STORAGE /storage/sdcard0
- mkdir /storage 0050 system sdcard_r
- mkdir /storage/sdcard0 0000 system system
- symlink /storage/sdcard0 /sdcard
- symlink /storage/sdcard0 /mnt/sdcard
-
# permissions for bluetooth.
chown bluetooth bluetooth /efs/bluetooth
chown bluetooth bluetooth ro.bt.bdaddr_path
@@ -74,6 +83,8 @@
write /sys/kernel/mm/ksm/run 1

on post-fs-data
+ mkdir /data/media 0770 media_rw media_rw
+
# wi-fi
mkdir /data/misc/wifi/sockets 0770 wifi wifi
mkdir /data/misc/dhcp 0770 dhcp dhcp
@@ -84,6 +95,10 @@
# ReadMin, ReadInitial, ReadMax, WriteMin, WriteInitial, WriteMax,
setprop net.tcp.buffersize.wimax 4096,524288,1048576,4096,16384,110208

+# virtual sdcard daemon running as media_rw (1023)
+service sdcard /system/bin/sdcard /data/media /mnt/shell/emulated 1023 1023
+ class late_start
+
service gpsd /system/vendor/bin/gpsd -c /vendor/etc/gps.xml
class main
user system
--- /dev/null
+++ a/device/samsung/crespo4g/overlay/frameworks/base/core/res/res/xml/storage_list.xml
@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!--
+**
+** Copyright 2011, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License")
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+** http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+-->
+
+<!-- See storage config details at http://source.android.com/tech/storage/ -->
+
+<StorageList xmlns:android="http://schemas.android.com/apk/res/android">
+ <!-- internal emulated storage -->
+ <storage
+ android:storageDescription="@string/storage_internal"
+ android:emulated="true"
+ android:mtpReserve="100" />
+</StorageList>

But it doesn't work sadly. It stops the force closes but the sdcard is no longer accessible. Haven't been able to get to work after reading through all the tracked changes in google's git repository. http://source.android.com/tech/storage isn't accessible either. Must wait till he shares the fix.