Havok animation supports blending between physical and keyframe animation very well. It also supports pose matching which help you to switch between physical animation and key frame animation without any glitches. Havok animation SDK provides all of the things you need for combining keyframe animation and ragdoll. However euphoria made the physical contacts intelligent. As far as i know It uses machine learning techniques to control biomechanical forces and make intelligent body collisions.
If you want to make intelligent body contacts you should make a system on top havok physical-keyframe animation blending. If you want to find more about the havok physical animation-keyframe blending, you may search about the "Powered Ragdoll Contoller" and "Rigid Body Ragdoll Controller" on havok animation SDK or havok animation tool.