Start across the creek from the Bull Hill
trail and follow the trail up a parking lot on route 407 (Trostle Pond parking lot). Cross 407 and continue on trail to the top of the hill. Cross route 438, and continue on trail to the dirt road (Austin Road).
It is a lot of fun when wet - the roots will take you out in an instant. When it's dry, ride it as fast as you can and you'll love it. Good in either direction.