Install Android 4.0 ICS on Galaxy SII i9003
Developers have made significant progress in making Full Android ICe Cream sandwich working on Galaxy S II aka i9003, thanks to @xplodwold. This is the first alpha build of Android ICS for Samsung Galaxy S2.
Note: Some of the stuff would not work: e.g. hardware buttons, camera, etc.
Install Android 4.0 ICS on Samsung Galaxy S 2
Pre-requisites: Rooted Galaxy SII
Step 1: Download the alpha 6 version of the Android 4.0 Ice Cream Sandwich ROM for Samsung Galaxy S2 from here. Copy ROM to internal ROM/ sd card.
Step 2: Reboot Galaxy S2 in Recovery mode. To do that, switch off the phone and press the Volume up + Home + Power button simultaneously to boot into recovery mode.
Step 3: Lets now wipe the existing data. partition select the ‘wipe data/factory reset’ option. Format the /cache partiton by selecting the ‘wipe /cache’ option. Next, Format the /system partition by going into ‘mounts and storage’, and then selecting the ‘format /system’ partition option.
Step 4: Select ‘install zip from SD card’ option, and then navigate to folder where you copied ICS zip.
Step 5: Once done, repeat step, yes its needed.
Step 6. Reboot and enjoy Ice cream sandwich!.
Developer is working hard to get most things to work. A new alpha version of the ROM should be expected tonight with calls, SMS and Wi-Fi working!