Just like the OB2 you got to set cust and press goto. Ok first find a corner inside the building u wanna ROB that you can LFG float to the top. When you find that corner get ready to let yourself float to the top. now let yourself hit the corner then goto your set cust menu as quick as you can so you can still set cust while you float to the top of the building. when you hit the OB on the top set cust. Like the ob2 you should not be able to stay on roof every time you press goto. Now go back to that corner and float to the top this time pressing Goto custom restart when you bail like the ob2. It takes some timing but u can get on alot of roofs like this.