The main work would be making this into a Fantasy Grounds font file. There is an Font Generator available in the "utilities" section of the downloads page where you can convert True Type Fonts (TTF) to FG fonts:
https://www.fantasygrounds.com/downloads/
Or, you can edit your own font using the font editor:
https://googledrive.com/host/0B27SCD...nt-editor.html
Then it is a case of putting the new font entry in the extension.xml file. e.g. if the new font is called thassilonian.fgf and you want the new language name to be thassilonian you'd add this entry:
Code:
<font name="thassilonian">
<fgffile name="fonts/thassilonian.fgf" />
<color value="#000000" />
</font>
Then using
/lang thassilonian Hello! in chat will use the thassilonian.fgf font.