There are a lot of games in steam working with x360 controllers but not mapped properly with a PS3 DS3 controller...
MotionInJoy do it clean with "emulate 360 controller" but it works only on PC. There is another PC-only project : x360ce : https://code.google.com/p/x360ce/
Here is the question : is there any solution for mac os x ? If not, why !?