Photographing glass and managing your light source, how to?

I found this photo on DA, it shows excellently the goal I want to reach in photographing glass, with the same subject matter.

http://www.deviantart.com/print/638000/

Where did this artist place (a) light source(s), or could you guess or give tips as to where good places are? Especially to get the definition not only on the clear glass, but the opaque glass too.
Sorry about the duplicated post, glitch.