There's only one route here: the ultra-classic Aiguille De Joshua Tree, an outstanding 5.6 boulder problem/free solo near the south end of the Lost Horse area. Bring along your cajones, untie from the rope, and head up a slender needle of rock. Make sure your friend has a camera along for the obligatory hardman summit shot.
Descend by downclimbing the route.
Getting There
Park and approach like you were going to Atlantis (park near the gate on the Lost Horse Road, south of the main park road, then start walking east), but instead of hanging a left into the Atlantis gully, keep going straight (veering slightly to the right). Basically, just follow the contour of the rock formations, and the aiguille will be right in front of you. You can't miss it.