walking through these pages with the huit/vagrant-generic CentOS 6.5 box
https://github.com/facebook/hhvm/wiki/HHVM-Pre-built-packages-for-Centos-6.5 https://github.com/facebook/hhvm/wiki/Building-and-installing-hhvm-on-centos-6.x
Install EPEL
rpm -Uvh http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm