Well if it's a auto you only need one, I would put it on the rear so you could flip the switch and lock out the rear brakes from being used during a burnout, That way you can control how fast you roll by letting off the brake pedal.
If it is a stick you need to one to lock out the rear like in the auto and on to lock the front in while you start the burnout, then once it started unlock the front and control the roll out with the pedal again.
Step 1. crus at it.
Step 2. get a hammer.
Step 3. torch it.