Making .ISO files on a Mac

Open Disk Utility

Select the partition of the CD you wish to copy

Click on New Image

Leave uncompressed but set the CD/DVD master option.

This will spit out a .cdr file which works only for Macs.

Next convert this .cdr file to a .iso using the command line:
hdiutil makehybrid -iso -joliet -o CDName.iso CDName.cdr