YUM remote repositories work well without any special handling that can be found in the Remote YUM Repository feature of Artifactory 3.6.0+. You simply point your Maven remote repository URL at the base of the remote repository and then configure your yum.repo.d file to point to your artifactory repository. For example, say you wanted to have a centos mirror, in /etc/yum.repos.d/CentOS-Base.repo there will be several entries with a baseurl like:
Set up a repo in Artifactory called, say 'centos' for the URL you give it
Then edit your CentOS-Base.repo to replace 'http://mirror.centos.org/centos' with something like 'http://artifactory:8081/artifactory/centos'. Then just do a 'yum update' to test it.