If the way it works in JK2 is anything like it worked in Heretic II, vaulting off of walls is relatively easy. It's a matter of jumping in the direction of the wall and then using the jump key and I believe, an arrow key to vault off of the wall in the opposite direction. I used to use this type of move to place myself behind opponents all the time in H2 bladematches.
~ Daedelus ~
"This ain't like dustin' crops, boy!"