I remember the 'illuminated gauges' days well! I remember converting my planes to that. It took a long while to learn, and still I didnt totally understand how it worked. What an awesome effect though.
Bill Leamings tutorial showing how he did the lightmap though is what really made it look real. A normal bitmap would have made them look like 'daytime' textures, but Fr. Bill's tutorial shows that you use a vanilla color, and lightly cloud the illuminated zones with an airbrush, leaving some dark zones in there for actual shading effects in actual gauges. THAT was the finishing touch and effected the 'entire' sim community with everyone advancing to illuminated gauges.
Another thing Fr. Bill was teaching us was multi-material mapping, something I also struggled with. His program (I forget what its called) would auto-arrange parts onto a single map platform. Then you did the art on the pattern that was created.