Parking is by the bridge (there are signs for Rec parking) and just ride straight up the road to the pits and grab onto a trail, or head around the first gate you see. From there, the possibilities are endless! Just remember, a few people make it nice for TONS of people to ride it. If you see s*** in the way, don't go around it, just pick it up and put it onto the side!
Route 15 East, after Johnson take a right on Church street, left onto Main street, bear right onto Depot street, and finally and right onto griggs road. follow that down to the bridge parking lot (you can't miss it)
http://www.singletracks.com/item.php?c=1&i=1844