Hello Nov2011. Hopefully this will be of some use.
Here is the way to use mental to get a wireframe only render for compositing...
https://youtu.be/-S2imhz0A6o
and here is the original tutorial to show how to create a material and turn on mental ray contour rendering in the materials shader group as well as in the global render properties.
https://simplymaya.com/autodesk-maya-...ya/?tut_id=199
"If I have seen further it is by standing on the shoulders of giants." Sir Isaac Newton, 1675