This glitch requires you to be the Jet Trooper. This also requires the Invulnurability Cheat, so it's not really useful in an actual game. To begin, head outside from Command Post 6. Follow the left side until you come to the outside of the large, outer circular center room. Head to the corner, near command post 5, between the outer circle and the tunnel connecting Command Posts 5 and 6. Face it, stand back a few steps, and rocket up to the top. You should be able to land on top. Now you can walk on top of the entire station, go behind the station, walk up the large mountains back there, shoot people in the center of the doughnut, fly into the corridors there, etc. However, if you do go in, you have to do the trick again. Also, you can fall inside the doughnut into a mine shaft like hole,