The most updated information for enabling EPEL should always be at the Fedora Project's Wiki.
In that page's section "How can I use these extra packages?", there are links to the latest versions for CentOS 6 (and CentOS 5).
In that page, download the .noarch file, for example:
wget http://www.mirrorservice.org/sites/dl.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm
Then, install with yum:
yum install epel-release-*.noarch