Your basic bunker piece code:
Code:
AddTerrainObject = TerrainObject
PresetName = Closed Tomb
AddToGroup = Bunker Modules
GoldCost = 50
FGColorFile = ContentFile
Path = Base.rte/Scenes/Objects/BunkerModules/TombAFG.bmp
MaterialFile = ContentFile
Path = Base.rte/Scenes/Objects/BunkerModules/TombAMat.bmp
BGColorFile = ContentFile
Path = Base.rte/Scenes/Objects/BunkerModules/TombABG.bmp
The first FilePath directs the bunker piece to the BMP that overlays colors over the bunker material. The second FilePath directs to the BMP that is composed of the materials that make up the bunker, based on the RGB values in Base.rte/Materials.ini. Finally, the last FilePath is what directs what BMP to use for the background.
You can see examples in Base.rte\Scenes\Objects\BunkerModules.