I figured out a way to add fonts to OOo relatively painlessly. There's a "hard" way and a potentially easy way. I'll outline the hard way first:
NB my OOo image is mounted at /opt/ooo
First copy the original OOo fonts directory to somewhere in your filesystem:
mkdir /mnt/hd/store/ooo-fonts
cp -a /opt/ooo/opt/OpenOffice/share/fonts/* /mnt/hd/store/ooo-fonts/
Map the new fonts directory over the original OOo one (so effectively that directory is now writeable under minideb/OOo):
mount --bind /mnt/hd/store/ooo-fonts/ /opt/ooo/opt/OpenOffice/share/fonts
Because minideb/OOo is not able to see your entire filesystem you need to map the pdaXrom fonts directory onto somewhere within the minideb filesystem. Something like this would do:
mount --bind /usr/X11R6/lib/X11/fonts/TTF /opt/ooo/lost+found/
(NB I chose /opt/ooo/lost+found because under minideb/OOo that is empty and unused)
Next you need to run the spadmin program, to do this what I did was make a copy of /usr/bin/runoo calling it /usr/bin/runspadmin, then edit it to change soffice to spadmin.
In spadmin choose [Fonts...] > [Add...], for "Source directory" navigate to "/lost+found", select your fonts, make sure "Create soft links only" is checked, then click [OK]. Once it's done, close spadmin, startup OOo and enjoy your new fonts.
Now for the potentially easy way, it seems that OOo's truetype font directory, ie /opt/ooo/opt/OpenOffice/share/fonts/truetype/ is just a "standard" fonts directory with a bunch of ttf fonts and a fonts.dir file. If so, you can just create and populate an arbitary fonts directory then mount --bind it over the original OOo font directory. This way you do not need to run spadmin.
-- cheers