Adding "airport" on top of a building

I created with ADE a scenery in which there is a building with an hard roof on top.
I would like to modify the roof of the building adding taxis with lights and perimeter custom lights.
I'm struggling to find a possible way to do it.
Any hint will be appreciated.
You will probably need to add the lights using 3D objects, probably library objects. You could add any markings using a 3D program like GMAX (creating a textured polygon and plopping it onto the rood).