Is there currently a backend that supports OTF GSUB features such as the choice between old style/lining figures?

I couldn't find a way to make this work, which is an issue for working with some "professional" fonts (e.g. FF Scala Sans Pro) that come with old style figures enabled by default.

Trawling the web, I found some references to HarfBuzz supporting specifying those with a colon after the font name, e.g. Scala Sans Pro:lnum in the above example. I couldn't make that work with the way matplotlib uses FreeType, though (haven't checked the source code yet).

I suppose I could use XeTeX via PGF, but that seems like a rather roundabout way.