How to hack playstation gamepads keys and use the Massage me touch pad as a button inputs. You can use other sensors as well. This version works only for digital inputs unfortunately. Analog input version will be coming soon.
First, unscrew all the screws on the gamepad and open it. The inside looks more or less like this (see picture). It also has motors for "Dual shock", but I took the picture after I cut the cable... sorry.