I'm not real sure about the multiple pad hacks. I guess it's dependent on if they all use 10k pots with 5k being centered.
I'm pretty sure the xbox 360 pad hack would work, but as you can tell from this thread, nobody has actually done it.

.....crap, there's only one of those ALPS 10k joystick still available on ebay

I'm looking elsewhere, but not finding anything.
I have enough amazon credit to get a wired xbox360 controller.
If I find a deal on useable joysticks, I may order everything and do some testing.
I'm not good enough to hack the whole pad, but I could probably get enough done to test the concept.
I'm a bit all over the place with my projects and have too many, so no guarantees.