How to incorporate OptiTrack NatNet SDK to stream motion capture data in to Unity?

We're trying to make a game in Unity using the mocap rig as a controller with OptiTrack Arena. It looks like the best route is to use the NatNet SDK/DLL and adapt it into Unity somehow, but so far this hasn't worked. There are a few errors, but mostly it just doesn't seem to do anything.

Has anyone worked with this before?

NatNet SDK can be found at this link:

If there is a .NET SDK you should be able to use it directly by putting the DLL into your Assets folder. If there is an unmanaged DLL you can call into it using the DllImportAttribute.

Note that use of external plugins is a Pro-only feature, and that making it work will depend not just on bringing the plugin itself into Unity, but all its dependencies as well.

More info in the Unity docs.

Good luck! (And please report back -- it would be interesting to hear from anyone who's incorporated external packages in this way.)