Can you not add the background in post, I do that a lot now in P6. I save the image as a png and then add the background in post as a photoshop layer. With IBL in P6 I can match the lights first in the render and then when I add the background in post the lights are right too. Doesn't work for all things but does for most. thefixer, poser coord.

Injustice will be avenged.
Cofiwch Dryweryn.