i used the rpm from the sun site:
https://jsecom16a.sun.com/ECom/EComA...83b3d158ab1568
which intall the necessary files to /usr/java/j2re1.4.2_04. then you have to create a symlink to the plugin in the mozilla plugins directory:
cd <mozilla install directory>
(in my case cd /usr/local/mozilla)
cd plugins
ln -s <java install location>/plugin/i386/ns610-gcc32/libjavaplugin_oji.so
(in my case ls -s /usr/java/j2re1.4.2_04/plugin/i386/ns610-gcc32/libjavaplugin_oji.so)
restart all mozilla programs (including main, newsgroups etc), and it appeared in about plugins