I found this technique from another rendering forum, corona (which btw if you use 3dsmax is a pretty damn vast unbiased CPU renderer in develop right now), for achieving a volume lighting render. It’s a hack but it possible to use right now.
Basically you use a plane that moves through the entire scene perpendicular to the camera, then turn on motion blur and increase the frame blending enough so that cycles is calculating the entire motion. The plane will catch the light and blend it through the whole scene giving the illusion of volume lighting. I used a mix of diffuse and translucent material for the plane but wouldn’t be surprised if there was a better material method. Here’s some examples:
They are noisy, and while not impossible it would not be easy to animate since you are relying on motion blur for the effect, but I figured if I share this with you guys maybe you smart blender folk can improve on it
fake volume_suz.blend (947 KB)