This is from the install page at java.
Mozilla 1.4 and later
1. Go to the plugins sub-directory under the Mozilla installation directory
cd <Mozilla installation directory>/plugins
2. In the current directory, create a symbolic link to the JRE ns7/libjavaplugin_oji.so file Type:
ln -s <JRE installation directory>/plugin/i386/ns7/libjavaplugin_oji.so
* If Mozilla is installed in this directory:
* and if the JRE is installed at this directory:
* Then type at the terminal to go to the browser plug-in directory:
* Enter the following command to create a symbolic link to the Java Plug-in for the Mozilla browser.
ln -s /usr/java/jre1.5.0/plugin/i386/ns7
3. Start Mozilla browser or restart it if it is already running. Note that if you have other Mozilla components (ie: Messenger, Composer, etc) running, you will need to restart them as well.
4. Go to Edit > Preferences. Under Advanced category > Select Enable Java
It should do the trick
If its done correctly, you should have a section beginning with 'Java(TM) Plug-in 1.5.0_03-b07' in about
lugins after a browser restart.