PSP-Hacks has posted a windows application to use with Edison Carter’s cheat device called CheatSync. This program basically allows you to sync your PSP with new cheats for GTA:LCS.
The cheats are arranged in the following categories:
Once you have selected the cheats you want from the online list you simply connect your PSP to your computer and from the CheatSync File menu click the Copy To PSP option… This will overwrite any cheats you have already installed so backup your list before you do this
You can download CheatSync here.