And then there was that wall! :-(

[ThatOneGuy]

Run at the wall, do a jump up and toward the middle of it, grab the top with both hands, use your momentum to boost out of a pullup into a dip(the exercise that strengthen's your triceps) - from the dip position, throw one or both legs over, twist, and boost off into a crouch/roll(insert optional ninja yell here ;) ). Or reverse the process on the other side to avoid possible hard landing injuries/ankle rolls.

If you dont have the strength, work on pullups and triceps. I do alot of climbing so this type of thing comes easy for me, but a little conditioning in pullups and dip excercises will do wonders for you. Its a pretty quick increase at first so you should be fine after a week or so.