have you seen MAX?
-and VBAP
http://legacy.spa.aalto.fi/demos/wwwvbap/
I am looking into the same thing - using Rhino for sound design, specifically 3D panning
http://discourse.mcneel.com/t/rhino-used-for-3d-surround-panning/32223
Please let me know what you find out, ok ? 