do you have FTP access to your xbox? if so tell me the file size of the gta3.img file.
Its late im bored I give it a whack I guess learned about trainers today but I guess I give it a shot
First off make sure you have the most up to date EvoX Version
1) Download the trainer you want from
http://trainers.evolutionx.infoor
http://trainers.maxconsole.com/2) Connect to your xbox and transfer the files that you downloaded to your c:/Trainers
3) Now reboot your xbox
4) If you have the default EvoX.ini ...then on the main menu in EvoX go to Trainers
5)Select the Trainer you want.
6)Now select the cheats you want..infinite health, infinite money etc....
7)Now go into Evo Settings and make sure you have
IGR-->Yes <-Not 100% sure if you need this
TSR-->Yes
Reboot
9) Now load your game using either DVD/HD
10) Thats It
hopefully that can help someone
feel free to add its late for me hehe