Good bye $519 price tag on a Roland SPD-S! This is all I need!
I really wish I would have made a video showing the process of this, but I didn't.
I just took a Rockband drum set, cut and soldered the wires so they were long enough to put the pads in a 16x16" square, and then I screwed it to a piece of wood. Then the drum set plugs into any computer (a laptop in my case, because I want to take it to venues) and then I set all four pads to do bass drops (because I made it for local drummers to use). You can add any sound effects to the pads, as long as they're in .wav format.
Here's a video: http://vimeo.com/22539220
Any other questions, just leave a reply below!