@ameho: Thanks for proving that this is actually working and feasible
. I'll try to look at it in detail during winter break, see if I can come up with a less cumbersome manner to make it work...
@chunchunchun: You can't through the UI. If you look at the basic fc-override.tpl fontconfig config shard, you'll probably be able to come up with something working, but having a basic understanding of how fontconfig works will certainly help.