You can mount the iso image using the -o loop
option, then act as it would be a mounted CD. You need to edit the /etc/yum.repos.d/Redhat-Media.repo (not sure about the name, since I have CentOS 6) and set the baseurl key to point to the correct location. You can leave enabled=0 in the configuration file above and use
yum --enablerepo=r6-media install package
again, not sure about the name of the repository, but you can see it in the aforementioned file. Hope this helps.