Installing PHP > 5.2.X on CentOS 5 using yum

1, import testing repository key
rpm --import http://dev.centos.org/centos/RPM-GPG-KEY-CentOS-testing

2 download CentOS testing repoitory
cd /etc/yum.repos.d/
wget http://dev.centos.org/centos/5/CentOS-Testing.repo

3 install or update
update: yum --disablerepo=* --enablerepo=c5-testing update php
or fresh install: yum --disablerepo=* --enablerepo=c5-testing install php

4, restart httpd
/etc/init.d/httpd stop
/etc/init.d/httpd start