DO WHAT NOW? Get your video game controller to do stuff in Live.
DO WHY? Because doing so is awesome. Duh!
DO HOW? This is where it gets tricky. But not that tricky.
MIDI or KEY mapping? Key mapping alone is groovy, but you are limited to toggling between two values. That’s no fun for a filter sweep! With 0-127 ranges you can map that analog joystick to control knobs and faders with full precision.