All,
I've written a new AC3D plugin for selecting surfaces in your scene with selected materials. Find it at:
http://supercoldmilk.com/ac3dplug/selmat.html
This is a Windows plugin. As with all plugins here, all source is available for compilation on other platforms.
See all plugins at:
http://supercoldmilk.com/ac3dplug/index.html
Dennis