You might be interested in a 'stage' setup I created as a virtual photo studio... see my gallery image (casual nudity advisory) Guinea Pig.

I modelled the two spotlights in the back corners of the stage using Poser primitives, and they incorporate two Poser spotlights. The overhead light is an IDL ambient surface light, again modelled using just Poser primitives, with a specular-only spotlight.

The modelled lights are parented to their respective Poser lights, and the Poser lights are pointing at a hidden 'light target' in the scene. So you can move each light or the light target anywhere around the studio, and the lights (both the models and the Poser spotlights) will always 'point at' the target.

bagginsbill's Light Meter that Miss Nancy mentioned is incredibly useful for quickly setting up good light levels and balancing diffuse and highlights.

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)