First off, this should be in the HOMEBREW SECTION. That aside...
Quake X has a problem with the config files, no matter what you do to them, they always get overwritten when you start the game, so if you analog is not working right now, go in and delete the config file and let Quake X make a new one, after the new one is make, exit the game, FTP into your XBOX, and edit the config file with notepad, use Notepad's FIND option to search for the word INVERT. It is set to 0, so set it to 1, then save and upload it back to your XBOX. This is the ONLY thing Quake X will allow you to change at the moment.
Lantus has this fixed, but is waiting to release the next version of Quake X when he has the OpenGl code all finished. <