One way this can be achieved, is to Composit the two in post (after rendering) if you have access to a program like Photoshop. This way you can try to match the two so they look like the were shot at the same time/place.

For that shadows, I beleive you make a plane in maya, and apply the "Use Background" shader, which will render out ONLY the shadow.

So you have you model, you're shadow-plane (with use bg shader) and you should render out to TGA (transparent) so all you have to do in photoshop is pull up you're test bg, and add you're latest render right on top. Then you can start playing with "Levels" on each layer to get them to match.

Sorry if I went a lil overboard.