Do you have a Photoshop script for selecting any colour ID?
I don't have but maybe quite easy to create but without the coverage pass will be hard to get nice results ....
check that link for the process is quite easy http://www.sigillarium.com/blog/lang/en/379/
to explain basically without aliasing we can select any coulour and extract then without issues then just multiply with the actual mask extract from the ID.
at Nuke is a quick script to setup. and we get really close results from a normal alpha rendered from the engine