I highly recommend watching this video and practicing the walljumps performed here, I especially like the elevator-tree-ridge one :) Here's what it says at the start of the video, I'll just quote
I [ZDS]GOUBO/radeonator2000 got sent this from a buddy called RADEON285 on UT2004 the speed he does this is amazing
I got sent this from my buddy RADEON285 it shows how to make the lev fly through walls and go hyperspeed (i suggest using 3rd person view)