Does Java's extension mechanism not work on OS X? I've creted a lib/ext directory in every place I can think of, but jar files that I put there don't get searched as they would under, say, /usr/local/jdk/jre/lib/ext in Linux.
OS X doesn't use the standard Java directory structure, so you'll have to hunt through the frameworks folders for it (I don't remember where it is) or just use classpaths a whole bunch.