1. Render a mirrorball in an empty sun+sky scene (http://www.indigorenderer.com/joomla/fo ... hp?p=27814 - images are dead

2. Next render the same scene without the mirror ball.
3. Render your scene using the envmap from #1
4. Render your scene again, with alpha map enabled.
5. Composite #4 on top of #2