so summarize it:
specular color tells you what it looks like (what color) when the light hits the surface.
specular level tells how much that surface brights when hit by the light. the whiter, the shinier.
in BC, with the _specular map you tell the color of the surface, when hit by the light. with SpecularCoef (I think that's the value), you tell how bright the ship is. the whole ship. in max you can separate the meshes, but BC will take the ship as a whole.
that said, you don't need to use a greyscale map for _specular. it can be colored.