To do a light map, just make sure that whatever you want lit is on the top layer...make the layer below that the active layer...make a new layer on top of that and fill with black...now you should have a black texture with the windows or whatever on top of it...save it as whatever_i. To apply it to the model, select the texture you want lit, then under self illumination, add the i_map. I'll see about doing a tut on this.