I've just worked out how to add guitar chords above the stave using ....insert....text. How can I then write a flat symbol rather than the word which takes up too much space?
I just use a small "b". I think some of the font packages on the Scriptorium may have slightly more stylized versions.
I think that the FretQwik font on Robert's site (http://www.icogitate.com/~ergosum/fonts/music-fonts2.htm) may suit your need (it includes letters, sharp and flat, plus elements to draw the chord, 6 strings only).
However, I prefer (because of habit I guess) to use the fretsa.ttf, fretsb.ttf, fretsc.ttf font files. You can find a link to them somewhere else on the forum, or with a search tool such as google (it leaded me to http://www.simplythebest.net/fonts/fonts/frets.html).
HTH!
The frets (a,b,c) fonts (per Marsu) are good fonts. I looked at them before I created my own FretQwik font. The only reasons for using FretQwik are (1) You need only one font, (2) You don't have to hunt for the fret diagram, since you create it yourself (it's easy), and (3) It includes standard alphanumerics plus sharp, flat, and other symbols for spelling the chord.