I have created a yum reposiory with yumex pre-release packages for Fedora 13 & 14
You can find it here : http://repos.fedorapeople.org/repos/timlau/yumex/
Just download the fedora-yumex.repo file and copy it to /etc/yum.repos.d/ (as root)
It will tracks upstream development very closely and there will be frequent releases.
I have started writing some better documentation for Yum Extender, check it here