MarianoDT is exactly right, I will just add the the lightmap would be something like mainhull_iD.bmp
Just 1 thing. I stuggle with this for like 2 months, then found out that my video card was just too outdated to render damage maps and light maps. The newest drivers available were 1998. I just mention that cause people were giving me tips and nothing worked. One thing to maybe check also was a tip from Pelican is to delete the x files. The game rewrites those but reloads a ship from the x files to save time. SO after you add maps maybe delete those.
For example: If a ship has files named feklhr.mod and feklhr_brk.mod , the x files read feklhr.modx and
feklhr_brk.modx