First cd to your plugin dir, which I believe is under /home/tc/.mozilla/ (something like rAndomLetters/firefox/plugins), then:
ln -s /usr/local/java/plugin/i386/ns7/libjavaplugin_oji.so .
This persists, if you have a backup or persistent home. I haven't used FF in a while, so I'm not sure on how accurate the path is.