Creating your own repository is relatively simple. You take a directory, dump some RPM packages in it, and run createrepo. See man createrepo for more information.

People often wonder how Revisor handles comps.xml group files.

When you create your own repository, essentially a third party repository, follow the directions in Section 6.1, “HOWTO: Add a Third Party Repository” to add the repository configuration to Revisor's YUM configuration, since your own repository is a third party repository as well.

See also Section 4.3.7, “Testing & Troubleshooting the YUM Configuration”