Adding new symbols - is importing graphic perhaps possible?

I'm looking to enter a symbol used by many wire-strung harp players but not standard elsewhere, a vertical column of 3 or 4 o's, touching in their stack. It instructs the player to use a particular decoration.
One suggestion was to pretend that each "o" is a lyric for three verses, and hope that the o's could then be moved, but this would take ages each time, so I'd like to somehow add it to a palate.

I'll be grateful for suggestions as how I might manage this, please.

Is it possible to import it as a graphic file, maybe, and add it in that way, for example?

Thanks for any help.