You would need to to make your own physics one way or another - and for true rag-doll - I'd anticipate: Velocities, Joints, Rotational Velocities, and gravity.
Answer: Yes Fact:Not Easy
If DarkPhysics $$ is your issue - then ODE is free, Newton is free.
The REAL benefit of DarkPhysics is that the library already is integrated so a lot of mesh code memory pointers and directx stuff is done for you (Meaning not only is the physics part done - so is the whole DirectX->Ageia Physx communication regarding the DarkGDK lib. Quite a bit happens under the hood for you. This is where Lee and Mike Johnson kicked serious butt.
The draw backs to Dark Physics - are some features available in Ageia Physx API are not available or don't work the same way:
Vehicles (Number of Wheels Fixed...I THINK its not with Ageia Directly)
Dynamic Mesh - Even the documentation says it doesn't work with all meshs and might get discontinued. I personally have yet to take a MODEL (Even Dark Matter) and make a dynamic Rigid mesh body of it and see it work at all. This irritates me as if I model an Egg, I want it to roll to its side if I place it face up. Not choose BALL or BOX.
also Note - that from what I saw in the DBPro sample of the rag dolls - random crashes are not unheard of...could just be the DBPro version... also the effect was kinda slow (But I have a slow vid card and PC - I'll give it that) but if I increased the gravity a bit in the DBPRo demo - the Rag Doll effect looked more convincing to me in my opinion.
