Shouldnt save games be incompatable of another user for trophies? On playstation if you copy another save file not made by your account you wont be able to get any trophies at all.

well the savegames are tied to a profile, but you can extract them on a PC, change the profile ID they are tied to, move them to your 360 and then play that save as if it was yours.
There are also programs that let you cheat the contents of the savegames themselves, as in changing the amount of gold a character has in its possession, adding experience points etc.

Since it's allowed to move the savegame to a flash drive and back, there isn't any need for a modified console.

After doing a quick Google search, I can confirm that this works on the PS3 as well.