If it has a common ground, it'll probably be easy to hack. I have had good luck re-assembling pads that turn out to have multiple grounds (and it's suprising how many do that). If you are careful, you can experiment and then back-out if it doesn't go well. Then again, for $5, it's cool even if you go horribly awry.
Test each ground with a multimeter and ensure that each ground for each button is the same (and close does not cut it as I found out). If it looks like there's one ground, then wire it up and try it.