building boost by holding the brakes just enough to keep the car still....brake boosting can also be achieved while moving as well, using the same techniques, more gas than brake obviously......

a brake boosting from a roll how-to i remember from a while back...

1. go to the best gear for whatever mph you are gonna race from

2. while still on the gas gently press the brake pedal, you'll want to press it hard enough
that it starts slowing you down. But to keep from slowing down you apply more throttle.

3. The harder you ride your brakes the more load you put on your enigine. the more load you put on your engine the more boost you will build. (keep an eye on your gauge)

4. And as soon as you are ready to start go WOT and at the same time release the brakes, and that lovely sensation of boost is already there waiting for you rather than you waiting for it.

The key is to find just the right anount of preassure to apply on each pedal but that becomes very easy with a little pratice.