XUL Help?

If anybody out there has experience using the Mozilla front-end language, XUL, and its support for localization, I’d love to hear from you — I’ve been working through O’Reilly’s Creating Applications With Mozilla book, and it seems to be riddled with errors in the sample code provided. I can figure out everything except how to import labels into a XUL file using a DTD from a locale. So if you know how to pull this off, give me a shout!