I have created a font for use in producing Roman numeral analysis. Here are links to download it in Open Type (OTF) and TrueType (TTF) formats:
The font requires no special software support, so it works with pretty much any program that can use fonts. I have tested it with MuseScore and LibreOffice, and I assume it will work in any commercial alternatives to these free and open source applications.
To use the font, just install it normally (e.g., on Windows, double-click the download file then click the "Install" button in the dialog that appears), then select and use it normally in your program of choice.
We may eventually add native support for Roman numeral analysis in MuseScore (perhaps just by incorporating this font), but for now. you can use it with any text element. You can can enter your analysis as lyrics or as staff text, and use the Inspector to select Campania as the font. You can then optionally hit the "Set as style" button (labelled "S") to make all text of that type use Campania. If you use lyrics, you can press Space to move to the next note while entering your analysis; if you use staff text, press Alt+Right.
Feel free to leave comments with any suggestions or problems you encounter using Campania!