This will get CWM on your device's recovery partition and wipe out your stock recovery. If you wish to keep things simpler, just install ROM Manager and "flash" the T-Mobile G2x recovery from there, it doesn't actually overwrite your stock recovery, but it will still let you boot into CWM recovery, only by using ROM Manager, of course.
** Not responsible for any damage done, obviously. **
Here is an initial test of CWM recovery for the G2X. You need to use nvflash to flash this, I've packaged it up for you and included a nice bash script to flash it, on Linux.
Hold VOL UP+VOL DOWN
Plug in USB.
The phone won't do anything, but you should see it under 'lspci'.
Then grab http://mirror.dal.tdrevolution.net/c...h-recovery.tgz
Extract it, and run flash-recovery.sh
You're not stuck on a software upgrade screen, when your computer says the recovery image was transferred successfully, just pull USB and you're done.
test2 - Properly mount /sdcard to the external SD.
test2 - Fix device name, should be p999 not p990.
test2 - Do not use custom recovery ui, navigate using VOL UP/DOWN and Power to select. (BOARD_HAS_NO_SELECT_BUTTON).
test1 - Initialness.