Assign Object ID by Material?

Hey all,

I have a request for a script (of if this script already exists, if someone could point me to it?):

Right now I can assign wirecolors by materials, which will give me basically a colorize image to work with (as long as I include a VrayWireColor elements when rendering). This can work ok for the most part but it's not perfect.

Better option: I have another plugin/script that allows me to manually assign Object ID's (used in conjunction with VRayMultiMatte elements) to objects BUT... it's tedious when I have a lot of materials/objects that I know I'm going to need object ID's for.

What I'm looking for: A script that will allow me to automatically assign object ID's to objects BASED on materials. So material A has object ID 1, material B has object ID 2, etc.

I tried taking a crack at this myself but I'm a scripting novice and... it didn't work at all. Any help? Advice? Pointers? Anything would be greatly appreciated :)

Also open to other suggestions! Working these renderings in Photoshop and selecting the materials by color via the WireColor render elements doesn't work as well as Object ID's (via MultiMatte render elements).