There is a tutorial I did a long time ago in Acrobat format that shows a lot of things about texturing in Max. At the time it was Max 3, but 4, 5, and 6 all work the same. One of the things in the tutorial was how to use multiple textures on one mesh.
The tutorial was specifically done for ship texturing. I am not sure where you can d/l it from at this time, and it is large enough that I don't have the bandwidth to host it.