I had a problem where I needed to install PHP 5.2 on a CentOS system, but by default, CentOS only supports up to PHP 5.1.6.
As posted here, one solution is to enable the CentOS testing server:
[quote]To enable centos-dev, you need to create
/etc/yum.repos.d/centos-test.repo and enter following lines in it:
[c5-testing] name=CentOS-5 Testing baseurl=http://dev.centos.org/centos/5/testing/$basearch/ enabled=1 gpgcheck=1 gpgkey=http://dev.centos.org/centos/RPM-GPG-KEY-CentOS-testing[/quote]