I would strongly suggest that you install MOBILE ODIN from the market and get familiar with it. Assuming you install it this is what you have to do: download the EL26 Kernel/CWM file. You will see every AOSP mention this file. It's hands down the most important file to have when dealing with ICS AOSP roms!
Open MOBILE ODIN. Select KERNEL. navigate to the EL26 kernel/recovery. select execute/run (or whatever the option is) It will have an optional MD5 check. Proceed with flashing.
The phone will automatically reboot. Steadily hold down VOLUME UP and POWER until recovery pops up. Once here you may want to back up your current rom or if that's not needed go ahead and do a factory reset. DON'T USE CALKULIN's FORMAT ALL ZIP (I understand it formats SYSTEM which is a problem for flashing AOSP roms like this one.) Once you have done a factory reset simply flash this ROM. Keep in mind that you are doing all of this in one session.
Once you flash this ROM you will no longer have a recovery. You will have to once again go to MOBILE ODIN and repeat the steps I outlined above. Hope this helps