Well I have Sun’s JDK installed, so I will provide instructions on this.
Download the jdk-6u1-linux-amd64-rpm.bin file: http://java.sun.com/javase/downloads/index.jsp
When the download is completed and from where the file resides type as root type:
chmod u+x jdk-6u1-linux-amd64-rpm.bin
./jdk-6u1-linux-amd64-rpm.bin
Press the space a number of times and answer yes at the end.
Next you will want to follow the instructions I provided in this thread:
http://www.centos.org/modules/newbb/viewtopic.php?viewmode=flat&topic_id=8390&forum=38
If you also want the java plugin for say the 64-bit version of firefox and/or seamonkey then download the file j2re-1.4.2-03-linux-amd64.bin from one of the mirrors listed here: http://ftp.cica.es/pub/java-linux/JDK-1.4.2/amd64/03/ located in the /JDK-1.4.2/amd64/03/ directory.
Copy the file to someplace like /usr/local (where I copied the file to) then do as root;
chmod u+x j2re-1.4.2-03-linux-amd64.bin
./j2re-1.4.2-03-linux-amd64.bin
mkdir /usr/lib64/mozilla/plugins
ln -s ./j2re1.4.2/plugin/amd64/mozilla/libjavaplugin_oji.so /usr/lib64/mozilla/plugins/libjavaplugin_oji.so