The Gc Script will change the aforementioned maps for either all materials, figures or props in an entire scene. 

If your skydome has an active ambient channel, even with no lights in the scene, IDL will still give you a lit scene. 

I see that you are using the original V4 skin textures.  To be honest, that is the worst node arrangement not suited for P8 nor PP2010.  I have always used BB's VSS skin template to enhance all my skin textures.  It responds better to Gc and all lighting conditions.  It has been recommended, strip out all the nodes and connect the skin texture directly to the PoserSurface node.  You will get a better render.