With the stock control arms there is very limited toe/camber adjustment than can be done in the rear. One pair of the arms (I think it's the front pair) has a large hex-shaped ****** that lets you turn an eccentric bushing at the inboard end of the arm. That's all you get for adjustment, and it doesn't have much of an adjustment range and barely affects the camber (it's mostly a toe adjustment).
If you're going to be replacing the arms anyway to fix the bent one, look into getting some GM arms off of a GTP and a sleeve kit from shonutperformance. This will give you fully adjustable camber and toe in the rear. If you really want to spend some money you can get the GTP aftermarket control arms from BRM fabrication (I have these on two SHOs, very nice).
Some of the SHO vendor sites have, IIRC, kits that include the arms and the sleeves together.