xCAT software and repo files can be obtained from: http://xcat.org/download.html
[xcat-core]
For the xCAT build you want to install, download the xCAT-core.repo file and copy to /etc/yum.repos.d
[xcat-dep]
From the xCAT-dep Online Repository, navigate to the correct subdirectory for the target machine and download the xCAT-dep.repo file and copy to /etc/yum.repos.d.
If using internet repositories, continue to the next step to install xCAT.