From the peak, head downhill on Main Divide Rd, a wide fire road littered with fist-sized loose stones. About 800 vertical feet and 1.4 miles later you'll round a wide-open, barren looking right-hand switchback that surrounds a large clearing. Along the left edge of the clearing, about a hundred yards after the turn, look for an almost invisible, 24-inch wide trail gap between two bushes. There is no trail marker, so look closely. This is the start of an extremely challenging black-diamond singletrack called Upper Holy Jim that, when combined with Lower Holy Jim, many consider to be one of Orange County's best mountain bike trails.
If you decide that Upper Holy Jim is too much for you, or for some reason you can't find the trailhead, don't fret. You can continue on Main Divide Rd for approximately 1.5 miles (I've never GPS'ed this section so the mileage is estimated by looking at maps) and Lower Holy Jim Trail
will be on the right, under the shade of a tree. It will have a small trail post marking the trailhead.