The same trick applies to the dust. Also, for the dust particles, I use similar code for the non-shadowed entity light occlusion. For the dust, I ray cast once when creating it towards any nearby lights, and do software lighting with a normal of <0, 1, 0>. I then blend between the dust's regular color and the color * the ligh color, and add the ambient.
I'm relieved that this worked so well, b/c I didn't want to kill the dust or do something more involved.
I debated lighting the dust even more accurately by using my old Averaged-L bump mapping idea and/or using the diffuse environment cubemap, but I'm trying to finish this, so that will have to wait for the next engine...
I'm working on the 1st actual game level right now, the Dig site where your character and the other members of your archeological team surprise & are attacked by lizard-like aliens.