dd if=/dev/cdrom of=your_image.iso

Ensure the mount point /mnt/cdrom exists.
To perform the mount:
mount -t auto /dev/cdrom /mnt/cdrom
If the symbolic link /dev/cdrom is not there, then try:
mount -t auto /dev/hdb /mnt/cdrom
replacing hdb with whatever your device is called.

With CentOS 5.2 (as ever), use the following to enable a listening tcp port (in this case 8000) to be accessed through the firewall.
sudo /sbin/iptables -A INPUT -p tcp –dport 8000 -j ACCEPT
sudo /sbin/service iptables save
sudo /sbin/iptables -F