One of the best gameshark/trainers software I have found to use with a modded xbox.
Covering over 300 games of both NTSC and PAL this will allow you to play almost any game with cheats on the original xbox.
Upload it to your apps folder using FTP and boot it. navigate the menu and enable the cheats you want, press start and with the game in the disk drive select the first option.
Unfortunately the menu items are in spanish. I don\'t know of an english version or how to change it. if any does please mention it in the comments.
if there are any other question feel free to ask.
have fun cheating!