> I've moved all development of this to a GitHub repository here: https://github.com/davidnalesnik/lilypond-roman-numeral-tool. There are significant improvements over what you'll find in the archives. Ability to do altered figures is one of the things I've added.
It's exactly what I need! Thank you!
> You can't do the isolated flat, but I confess I've never seen that notation used with _Roman numeral_ notation, rather only within pure figured bass.
It's used in "Harmony and Voice Leading" by Aldwell/Schachter.