yo, peteman, i think ur thinking of action replay and xploder cheat systems . the gta cheats device is done by edison carter. its available on many gta psp sites. this is edisons own one:
http://maxbot.com/gta/some things not to do are : spawn any kind of bike. if you try to get on the game can freeze and dont spawn rc things either. considering their size, tony is too big and the game freezes. there is also a list of pedestrian outfir spawns too but i dunno where. one more thing, if u walk thru a wall with the cheat and start falling, dont worry, u most likely will land back on a road near where u fell.