This seems to be the simplest description of setting up a fallback font I’ve found: http://weblogs.java.net/blog/joconner/archive/2006/09/internationaliz.html

We occasionally come across clients with the problem of fonts not rendering correctly in the JRE so in future I’ll be able to point them to this article. Fortunately, with Java 1.5 a pretty good fallback font is already provided so it’s pretty rare that you need to do this these days.