just wanted to add that:

• bill's shader incorporates the reflect/blinn module which allows specular surface fx with either diffuse sources or directional sources
• preview spots can have deceptive behaviour in some versions, e.g. seeming to go thru solid walls

the problem with gels is another issue, meaning the vent spot would still need to have whatever is blocking it removed. if one can download this scene file somewhere, the experts may be able to help set up the lighting.