http://www.clearfoundation.com/docs/howtos/adding_tim_s_repo
Please note these are not the official packages, and have been put together by http://rpms.famillecollet.com/ for RHEL5 distributions (thank you!). I have rebuilt these so they install for ClearOS with the addition of two RPM's (libedit and sqlite2).
You can also install many other PHP features through YUM.
yum install php-* yum list php-*
for all the available extensions you can add.
yum --enablerepo=timb upgrade php
yum remove php-*