The following updates PHP to 5.4 as well, so make sure you want that before upgrading.
The following has been tested on a CentOS 6.6 server with Plesk 12. I see you are running CentOS 5, run these commands at your own discretion. I haven't tried this process on a CentOS 5 box.
Thank you very much I'm using Centos 6.6 but I don't want to use ssh shell so I want to change with autoinstaller.
Can Plesk support Centos 6.6 with autoinstaller? Meanwhile changelos says (On Centos/RHel 5) you can chance log to (On Centos 5 and RHel 5)
Thanks again.