Basically its nothing more then a lightmap, but you need to insert the work (lightmap for instance) in the model before exporting it to FS. Thus if you do not have lightmaps assigned to the materials in the aircraft, then you will not have anything show up. Thats the down side.
There are some subtle tricks to lightmaps that you can do.
1. For older aircraft, use a yellowish color for the light zones.
2. You can colorise it to red if you like on modern planes, such as a new Piper, etc.
3. You can lightly illumine the surrounding area's if you like, say a cascade of white from a lightbar (located under the dash hood) that flows down the panel from the top, fading towards the bottom. This can take some learning to do. One way is to make a layer above the work, make a rectangle, then use Blur/Gausian Blur, and blur the heck out of it, and then lightly erase the bottom to give it an appearence of fading.
Slight colorizations are good too. For instance, if you have a blue faced Attitude indicator, then a light blue light will appear on the rim of the Attitude indicators bazel rim. On a Garmin screen surround, or military jet fighter readout screen 'rim edge', you can slightly colorize the inner edge to appear that the glow is cascading off the inner edges. A cool little touch.
So much you can do.
If the interior is light-mapped also, you can add some cool glow zones from instrumentation and things. At least give it a 5% glow so you can see a bit in there at night. Only shows when the instrumentation is actiavated.
Bill