I maintain RPM-packages for PHP 5.4 and 5.5, see earlier post about it.
As any sysadmin can expect, there was too much trouble running the updates. Since CentOS 6 native way is running yum repositories, I created one.
Kick things going by installing the repo-definition:
yum install \
http://opensource.hqcodeshop.com/CentOS/6%20x86_64/Parallels%20Plesk%20Panel/plesk-php-repo-1.0-1.el6.noarch.rpm
After that, a simple yum install command:
yum install plesk-php55
... will yield something like this:
/opt/php5.5/usr/bin/php -v
PHP 5.5.9 (cli) (built: Feb 9 2014 22:04:05)
Copyright (c) 1997-2014 The PHP Group
Zend Engine v2.5.0, Copyright (c) 1998-2014 Zend Technologies
I'll be compiling new versions to keep my own box in shape.