Hi Bryon,
Volumetrics, I call God-rays, for me is fog. And if you have fog, you can do this. Thea Render uses two types, a fog setting in environmental control settings as well as object based volumetrics as "cloud". We can set the camera outside this object (which renders as translucence/transparence that can be adjusted) and the sun effects all that is within that object. This works for small rooms where you want the God-rays coming from the windows, stretching to the floor or wherever depending upon where you set your sun. It's worth experimenting with.