custom font for special playing technique

I need to make a playing technique by using a custom font.
The font is a fingering chart for sax, clarinet etc.
I need to be able to type something like 3fdsjkz; and apply it to that specific font in order to display a chart for a specific fingering. Unfortunately if I create a playing technique with at text I can’t specify a custom font.
Any workaround?

Does it definitely need to be a playing technique? If not, you could do it as text. While it wouldn’t live in a menu, you could always create an extra flow at the end of your document to just hold your different charts for easy copy-pasting.

Tell the Playing Technique Editor you want to use a glyph. This will allow you to use one or more glyphs from any font you like, organised however you like.