1) I don't own an Epic Touch or a SGS2 device of any kind.
2) As some may be aware, many Samsung devices do not have and/or properly use a recovery partition. Instead the recovery is packed as a second ramdisk or as a separate recovery.rc in the same ramdisk in the boot image. This means that every time you install a new ROM or kernel, you will get stuck with whatever recovery is included with the boot image.
3) We do have a process that lets you inject TWRP into boot images that are still using the dual ramdisk setup typically found in CM7 boot images. I believe that somewhere along the development path of CM9, the boot image packing method changed to a single ramdisk with 2 init files (recovery.rc). This type of setup is much more difficult (if not impossible) to do "injection" and since I don't have a device in hand to work with I have no plans to attempt to create an injection method for this new type of boot image. The injection process still appears to work on CM7 boot images and some kernel devs for SGS2-type devices have not moved to the new method (yet).
4) We now have code that compiles in CM9. This new code base is much simpler to get started with - you just replace the bootable/recovery folder with the TWRP source code and grab a copy of our slightly modified 1.20 busybox code and you're ready to compile TWRP after adding a few build flags to your BoardConfig.
5) The TWRP source code is all public, including the GUI. It's pretty easy to compile and work with and we have a nice guide to help you out here: http://tinyw.in/nP7d
If you need help integrating TWRP into your builds or have questions about compiling TWRP, feel free to find us in #twrp on Freenode. TWRP works very well with thew GooManager app and if you host your ROM on http://goo.im, your users can receive notifications of ROM updates and easily download and flash the update almost like a regular OTA update. In addition, http://goo.im now supports automatic differential zip creation. You upload an update to your ROM and goo will create a zip with just the changes. Your users get smaller downloads, faster installs, and less wear and tear on the device since only the updated / deleted files get replaced, but this functionality is only easy to use with a supported recovery like TWRP. Please consider adding TWRP to your builds and using http://goo.im and GooManager! All of this functionality is free to you and your users!
If you're feeling really adventurous, you're welcome to install this for the Epic Touch after installing a copy of CM7. I was told by a tester that it was working fine but use at your own risk and be prepared to Odin / heimdall a working boot image if something goes wrong! Note that backups and restores done in TWRP / CWM are not easily interchangable!
I can probably create the same kind of a zip for SGS2 International if someone is willing to stop by #twrp on Freenode to test it. I do know that someone has successfully tested a ramdisk on the SGS2 with Exynos so TWRP should work on this device with relative ease.
Also note that it appears for the time being that most Samsung devices released in the USA where all team win members live, are going to be using Qualcomm chipsets instead of Exynos. This means that the only Samsung device that's readily available in the USA that uses the new boot image methods is the Epic Touch. We have a release for the AT&T Galaxy Note and Skyrocket but both of these devices use the Qualcomm chipset which uses a "normal" and separate recovery partition.