sitting on the start of the hill if you look to your right, that ridgeline is where the trail loops back to finish. the trail is marked with green paint on the rocks. there are a few bail out point that you can cut the distance down as well.
Head west on summit valley rd. passing the hesperia airport on your right. take the first paved tun off to your left that takes you to a hill and a parking area in front of the aqueduct. parked, enter the aqueduct and go around the paved road to the other side. take the aqueduct rd. for about 1.5 miles and you will come to a road bridge that crosses. take the paved road just off to right that travels to the top of the hill and this is the start of the green trail.
http://www.singletracks.com/item.php?c=1&i=8884