1. Download JDK RPM from Oracle

2. As root:

$ chmod +x jdk-6u30-linux-i586-rpm.bin
$ ./jdk-6u30-linux-i586-rpm.bin. 

3. Re-link to new JDK:

$ /usr/sbin/alternatives --install /usr/bin/java java /usr/java/jdk1.6.0_30/bin/java 16030

or alternatively: