1) Saw the existing button lengthwise so you have the two pieces moving independently, relocate and raise the original microswitch so only the top one hits it then add another switch.
2) profit.
Odroid-S rocks, the controls are a bit of alright, if and a big if, you don't smash the hell out of them like an f200, with a gentle touch the dpad is ok and works very well. Have not hit any maneuvers I could not perform with it yet.