As you may or may not know silverlight requires you to pack fonts with your application in order to use fonts that are not preinstalled with silverlight. The fact that these fonts would then be downloaded leads to licensing issues.
There is a way around this called obfuscation which is the act of creating an xps document and typing out all of the letters/numbers/characters that you need. Once you save the xps an .odttf file is created that allows you to use the font but does not cause it to download locally.
As you can imagine font obsfucation is a pain in the rear end. I created a tool that creates an xps file for you and places a .zip file on your c: drive so you can nip into the resources directory and grab the file.
The tool is currently in Alpha and more changes are to come but for know give it a whirl. It needs the 3.5 framework to work and comes with source included. It is pretty resource hungry because of the XPS creation but since it is only used for a few seconds its bearable.