Edison was able to pull this off since GTA:LCS is basically just a port of another GTA game with the "story" changed (hence the "hunter" and "dodo" models are still in the game). So the same code that he figured out for the other GTA games works in this one too. He basically "ported" his savegame hack over to the PSP with a few changes.
Fanjita took the code Edison gave him (?) and made it do more.
Hmmm...wonder if that would be possible on PS2 GTA games to run homebrew from there?
It's a neat hack all the same.