Applying Force to limbs of a ragdoll.

Lets say I do a trace onto a ragdoll. How can I apply force on the spot that the trace hit on the ragdoll? I was thinking it would have to be limbs, but the first way would be better. How do I do either of these methods?

first get the physics bone from the trace (http://bananatree.im/wiki/wiki.garrysmod.com/index1e71.html?title=TraceRes)

then get the relevant physobj and apply force to it: (http://maurits.tv/data/garrysmod/wiki/wiki.garrysmod.com/indexb3bf.html?title=Entity.GetPhysicsObjectNum)

thanks works perfectly.