In reply to zakmacro: I would be a little wary of this. Probably perfectly safe, however, an internal lightweight block wall may not have been designed to give any kind of side loading to speak of. If it were me, I would drill a couple of holes in the mortar, at three consequetive beds and see if it has tramlines in it for 'crowd loading'
Also, is the wall stable?
I personally would not trust expanding bolts taking a dynamic load in lightweight block since they could come loose over time.
I would fix plywood or timber rails to the wall using chemical anchors and fix your holds to that.
But.... all this is looking at it from the ppoint of view of engineering it so as to be perfectly safe.
You'd 'probably' get away with less.