I asked the same question weeks ago, and it is possible to integrate a mods even with copyright, but, it would probably be hard to make a copy because the content on GT5, like every other PS3 game, has yet to be cracked(I don't know if the PSJailbreak would count, probably not because it's not deciphering the game's coding.)
In other words, it might be available when an advanced hacker finds the template within the disc, which is not legal unless there is ownership of the original copy.
I hate to make minute piracy allusions, but this might seem like the case.
EDIT: PSJailbreak might do some deciphering, just not high intricate decoding.