Switch off the stability system and select shift program six. Switch the engine to sport mode. With the hand shifter in drive, hold it in the downshift position and press the gas pedal. The engine will rev to the preprogrammed rpm and hold. Now release the shifter. The car will launch forward violently and the engine's revs will climb quickly, so be prepared to upshift.
edit: this is apparently supposed to be a video of the launch:
haha, found a video tutorial from BMW:
BMW M3 Launch Control Tutorial - http://youtube.com/watch?v=boVK0O3zq...h=smg%20launch