Poul,

I downloaded a few models as OBJ and 3DS files. When inspecting the files I notice that the OBJ files have no MTL files included. Inspection of the OBJ file with a text editor learns me no MTLLIB is specified, and no texture images are included in the ZIP-file.

You could try to import these files in Blender or Art of Illusion and apply textures yourself. You could even try to add the MTL specs in the text file using a text editor.

Hans