root@CentOS ~]# mkdir /backup/
[root@CentOS ~]# mkdir /mnt/cdrom
[root@CentOS ~]# mount /dev/cdrom /mnt/cdrom

[root@CentOS ~]# vi /etc/yum.repos.d/CentOS-Media.repo

# Edit ------
[c5-media]
name=CentOS-$releasever - Media
baseurl=file:///mnt/cdrom
        file:///media/cdrom/
        file:///media/cdrecorder/
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5
# End  ------

[root@CentOS ~]# mv /etc/yum.repos.d/CentOS-Base.repo /backup/