Antonio made this test still render:
The best way to achieve a good integration was matching the same lighting conditions using a spherical high dynamic range image (HDRI). I got one of these mirrored ball on amazon, these are used as garden ornament, pretty useful though. This one is too small so it was hard to get a sharp image but in this case we don't need that extra level of detail for lighting and reflections.
I used a bracketed sequence of pictures with diferent exposures, merged to HDR in photoshop and warped to spherical panorama in HDRShop.