I just pushed a change which introduced a "Glossy coating" panel similar to the "Alpha transparency" panel. It adds a "glossycoating" layer using the material as a base layer. This saves one from having to create a mix manually.
It works with with alpha transparency as well, see attachment.
The change was somewhat intrusive due to the IOR preset menu being a bit hardcoded. So I had to duplicate some bits of it. It wasn't pretty, and should probably be refactored a bit by someone who's not a complete python nub, like me
Hope I didn't break too much.
Also note that the reason I pass the partial name and full operator name is that draw_generator didn't work when the operator name wasn't a string literal. Bug in EF or Blender?
May contain traces of nuts.