Download j2re-1_4_1_02-linux-i586.bin from
http://java.sun.com
Copy it to the dir you wish to install it to, I copied it to /usr/local/etc
chmod a+x j2sdk-1_4_1_<version number>-linux-i586.bin
./j2re-1_4_1_02-linux-i586.bin
Hold down enter while it scrolls through the license agreement. Follow the steps from there..
Now the messy Mozilla part
Create a simlink in your Mozilla install directory (/usr/local/mozilla) to libjavaplugin_oji.so (/usr/local/etc/j2re1.4.1_02/plugin/i386/ns610)
I hope this helps ya