Hi mystic80.
I have managed to get custom streetlamps working:
Try renaming your p3d to Lampa_***.p3d (*** = your lamp name). Also try naming your class something like this: Class Streetlamp*** (*** = your lamp name or similar).
So far I haven't managed to change the brightness of the lights but the lights work when placed on a map using Wrptool.
Hope this is of some help.
Cheers
Late edit:
By creating lights set at a certain height, say average room ceiling height I've managed to get some lights inside buildings (inlcuding BIS hanger), but these are dependent upon all ceilings being the same height. Also brightness is a concern and altering the following doesnt seem to help:
colorDiffuse[]={1.00000,0.90000,0.600000};
colorAmbient[]={1.00000,0.90000,0.60000};
brightness=0.75;
So far I have several street light models and runway lights but until I can change color and brightness they aren't much use. But still worth experimenting with.