callout.unicode.font question

Hello,

I would like to use a unicode font for my callout which are some time up to 20. I found NumberPile <http://www.dafont.com/numberpile.font>.

In <http://docbook.xml-doc.org/snapshots/xsl/doc/html/callout.unicode.start.character.html> we can read that the only start value supported is 10102. But in NumberPile the 0 is in 41 (A).

Is there a workaround to change the start character ?

Thanks in advance,
Jacques