Briefly? Jet up "close" to slopes while tapping jump. When you're over the top, kill the jets and tap jump quickly and repeatedly. If you're in the 3rd person perspective your guy will be doing a little knee-bent hop so you know it's working.
At least that was how I did it in the barely patched version ages ago. What version # are they up to now? Are they still having problems with asshsles doing DOS attacks?