What you can do is to edit the /etc/fstab file to allow all users to mount/unmount those drives by simply adding a "users" line to the ones you want. Your /etc/fstab should have lines that look something like this:
/dev/hdc /cdrom cdfs ro,noauto,exec 0 0
to remedy the mount problem - add a "users" to the third column.
/dev/hdc /cdrom cdfs ro,noauto,exec,users 0 0
This should allow a normal user to mount the cdrom drives (and it works with anything, so a normal user can mount a HD with this too)