Looks like you need to do the following:
"Put a symlink to /usr/java/jre<version>/plugin/i386/ns610-gcc32/libjavaplugin_oji.so in your plugins/ directory. (Note: copying the file instead of making the symlink will cause Java to crash.)"
So for example, on my system I would cd to /usr/lib/mozilla-1.6/plugins and then enter:
ln -s /usr/java/j2re1.4.2_03/plugin/i386/ns610-gcc32/libjavaplugin_oji.so
I hope this helps.