Morphloader Pro (Adv Figure Setup Tools) & Zbrush is probably one of the easier (albeit expensive ways to go.)

http://www.youtube.com/watch?v=SUU9vSJn-ko&feature=related
http://www.youtube.com/watch?v=jfA803Pqc08&feature=related

It uses "reverse deformation" calculations to so you can edited a posed & morphed part or parts (not just the zero position with no morphs).  It also builds the ECM calculations for the so that the correction morph is slaved to the joint movement.

I've used it a few times and it is (relatively) bullet proof.

Poser8/Poser 2010's stuff is good for fixes on the fly.

-K