First, go to Oracle and look for the rpm of java but, for x64 (good luck :)).
Install it normally, like any other rpm.
# rpm -ihv javaxxxxxx.rpm
Now we must work manually..
Create a symbolic link to allow use use it in Mozilla.
# ln -sf /usr/java/jre1.6.0_13/lib/amd64/libnpjp2.so /usr/lib64/mozilla/plugins/
And create your own link to it, like with:
# mkdir /$HOME/.mozilla/plugins # ln -sf /usr/java/jre1.6.0_13/lib/amd64/libnpjp2.so /$HOME/.mozilla/plugins/
and launch firefox.