Hi, MM:
Sketchup heretofore does not do lights, or caustics. It is not a rendering program. You could create a material/texture from a picture of a blazing light bulb, but it would not impart any effect on the surroundings.
You mentioned Kerkythea and Light Up which are both good rendering programs.
Look at this forum page:
http://sketchucation.com/forums/viewtopic.php?f=81&t=3220#p15472
Maybe one of those?