There are few good tuts that works for CentOS 5.6 with php53.
Jacob from dynamichosting.biz wrote a good guide to install ssh2 extension for php53 that worked for me.
Than follow these directions provided by Johnathan Dingman.
After you succeed with install, have a look at this Codex Page and make amendments to your wp-config.file to perform further updates with a single click.
All credit goes to these fine gentlemen mentioned above. I will only remind you not to be afraid of a bunch of warnings when you install php-pear. Force install and may the Force be with you.