ZBrushCentral

Can I assign different levels of opacity to a single subtool?

I sculpted a wine bottle encased in an elaborate loose macrame weave as a single subtool. I want to do a single pass BPR render where the woven material is 100% opaque and the wine bottle is semi-transparent.

I know that you can paint multiple materials on a single subtool.
-Can I assign different levels of opacity to a single subtool?
-Is there a material designed specifically for that?
-Or do I need to separate my object into separate subtools?

Thanks