Okay, so I took apart my ps3 controller tonight [my god, the innards are atrocious...] Little plastic bits and pieces go flying out all over... not even going to attempt putting this thing back together.. However, as a result of the odd construction, which includes a daughterboard comprised of a thin material, it looks like the majority of this mod is going to be easier than I had first expected.
The traces are easy to follow to find out which is for which button and it shouldn't be too tough to make new connections where this daughterboard connects to the rest of the controller. The biggest challenge will be moving the left joystick into position. The right joystick can be lined up almost perfectly without being moved.
Anyways, I'm new to soldering and have never really attempted a mod like this so progress is likely to be fairly slow... Any tips or any sort of help would be greatly appreciated. One of the things I'm not so sure of is how to efficiently connect multiple buttons to their common ground..