Using UMDGen, this shouldn't be too hard. I've found the BGM, module (I think this is fonts), and video folders.
I can't find the voice files, so I'm going to try to swap the BGM folders. If it doesn't change the voices, it shouldn't damage the BGM since they're the same from game to game.
I can't find the voice files, so I'm going to try to swap the BGM folders. If it doesn't change the voices, it shouldn't damage the BGM since they're the same from game to game.