Here is the directions from the Saddle Peak page...
"Stunt Road Trailhead:,
As for the Backbone trail, take the 101 North from LA to Las Virgenes Road Exit near Malibu. Drive south along Las Virgenes and turn left on Mulholland Highway. Drive approx. 5 miles, take a right on Stunt Road and the trail intersects the road just past the 1.00 Mile Marker at a "pull out". The trail intersects the road again at 2.9 miles."
The area is not in any guidebooks. We only did two routes, the one in the picture (5.7) and another just to the right, that was about 10a. The sandstone is pretty good though there is a bit of lichen and vegetation, but it's a nice place with easy access, and most likely you'll have the place to yourself. Like Melbatoast said, it's about a mile up the Backbone trail from the Stunt Road trailhead 2.9 miles from Muholland Dr.
It's off the 2.9-mile Stunt Rd. trailhead. It's about a mile in along the trail. You can't miss it. There's about 10 routes along the wall to the right of the trail. Don't know the names or ratings, but this one's about 5.7... Have fun!