Formatting Roman-numeral analysis chords with digits on top of one another

I'm working with MS 2.1.0, rev. 871c8ce on a Mac Sierra (10.12.6), and I've spent quite a bit of time going through the Handbook and the forums, but have not found an answer, so if this is a naive question, I promise it's not for lack of my trying to investigate it independently.

Based on the advice in one of the forums, for adding Roman-numeral analysis descriptions I just use the Lyrics text. It works very well with one exception: I cannot "stack" digits on top of one another in describing, say, inversions of a seventh. With a root-position seventh, it's a piece of cake — there's a "superscript" button in the character-entry palette. But if how do I put a six on top of a four or a five? It works so beautifully with the figured-bass function that I keep thinking there must be a way to achieve the same formatting effect in Roman-numeral notation. Help!