edisoncarter from GTA forums.com has released a great cheat device for GTA: LCS (North American version only)! When you download it it looks like a game save but works as a program in the background of your game.
The basic cheats implemented so far are:
Infinite Health and Armor
Set Wanted Level
edisoncarter says “Yes, the Hunter is in the game! To fire the chain gun, press SQUARE+X. Be careful with the spawn choices, some of the silly stuff to spawn like Ferry, Train, and the later Dodo choices will crash your game. Dodo 164 is the one that works. I left the full list in so people can have their own go at trying it. Maybe the boat spawns only work near water, for instance.”
This works on FW v2.0, 2.01. Everyone trying on 2.50 has had no success unfortunately. Although edisoncarter is confident of addressing this in a later release.
Unzip the archive to your memory card so the files go in PSP/SAVEDATA/ULUS10041S0. Remember this replaces the first GTA save on your memory card so you may want to back that up.
To start CheatDevice, simply load it like a saved game. Do not load CheatDevice again when it’s already running! Your game will probably crash!
You’re supposed to be able to load another game save while CheatDevice is running, but it sometimes crashes. At least you can load the CheatDevice save and play around in there.
Disclaimer: THIS CAN CRASH YOUR GAME, SO USE IT AT YOUR OWN RISK. Don’t use this for doing missions or when you’re planning to save your game.
You can get the trainer from the PSP updates download section here
Or you could get it here