Go to the large rocks at the back of the map and find the rock with a black spot in the corner on the back side. The rock is close to the large red tank-looking cylinders. Once you find it, go to the corner with a black spot and look down at it. Start to move to the left while moving forward. If you start to jump up and down without pressing X, you are doing it correctly. Once you begin to jump, run forward or to the right to push into the rock. Enemy air support cannot hurt you, though you can get killed by enemies and grenades if you are close enough. It is recommended that you bring a Tactical Insertion because people may discover you are there. Also, use a sniper rifle.