Radiance and MentalRay

All-

A colleague has given me a few simple Radiance scenes, and I want to try rendering them using MentalRay. Here at the lab, we have Maya and MentalRay set up, and I know it's easy to render Maya models in MentalRay. But so far I haven't found any way to convert the .rad files to something usable by Maya or MentalRay, and I'm not at all experienced with any of these three packages - this is just a small step in a much larger project. I'd be very grateful if someone could point me in the right direction.

Thanks much,
-crispy