it just takes time. make sure you let go of crouch while your crouching on the ramp by middle BR, and also when your turning around to jump on the side of the ramp try to look as little right as possible. keep your view as left as you can. jump right before the ramp ledge becomes diagonal
http://www.youtube.com/watch?v=iOWAC5uPW5c&feature=relate d
that should help
[Edited on 01.22.2010 6:22 PM PST]