What is the best way to control a ragdoll?

I've developed a relatively light character under Unity's Ragdoll system, with a skeleton and intentionally low-poly model. The ragdoll works fine, but now I'd like to control it with the mouse. At the moment I'm thinking twist the character left and right via the spine, but I'm not really sure of how to make this work. Just applying rotation to the bone causes it to spin wildly.