I had to copy a CD (this was at work, and it was an image we owned, so there were no copyright ramifications) today, so I wound up getting a crash course in disk mounting.
disktool is the command line tool for manipulating automatically mounted media, like CDROMs. Before you can use dd to read a CD, you must unmount it. disktool -u disk1s0 will unmount the CD from your desktop. You can then dd if=/dev/disk1s0 bs=2k | dd of=diskname.iso bs=10m will copy the CD into a file called diskname.iso. ISO files can be used by Disk Copy to burn copies.
Once you're done reading the image in, you can use disktool -e disk1s0 to eject the CD.