I have done some work on this again. I figured out the ccmesh_pc file has identical information as the matlib_pc file, but it refers to the low-res materials that are default for the characters. All at the end of the file. I've managed to create a proper material parser, and I managed to use scanti's SR3Unpacktextures tool in combination with the maxscript to automatically unpack the textures. So now we have automatic material creation!
Many models now successfully import, apart from a little few. So there is still a little tweaking that needs to be done. Other than that, things are starting to get somewhere!