new buttons xbox controller

[Moriarty]

I am interested in wiring two new buttons into/onto my xbox controller that can be struck with my ring fingers so that i can jump and melee without ever having to remove my left thumb from the joystick. Any advice on how to wire them into the existing board (preferably maintain the integrity of the original buttons). Also any advice on what buttons might be better than others and where to purchase would help. I was just going to begin at radio shack, but like everything else in the world I know there is a better resource on-line. Thanks again in advance for any help with this, i have become obsessed with this project.