During the landing rollout in gusty crosswind conditions, the commercial pilot was attempting to keep his single-engine, tailwheel-equipped airplane on the centerline of the runway with rudder input and aileron control when he inadvertantly applied too much pressure on the heel brake. This caused the tail of the airplane to rise. The tail hung breifly in the air before the wind carried the airplane over on to its back, which resulted in substantial damage to the left wing strut and vertical stabilizer.