So you’ve got a PC without a CD-ROM drive. (Err, DVD-ROM, DVD-RW, whatever). Or you bought a new PC motherboard without realizing it lacks an IDE port for your antiquated DVD player. Then you bought some software on physical media like it was the 90’s. (Perhaps you got a great deal on tax software, for example). So you have a Mac that has a DVD drive, and you’d like to copy the installer off the Mac but when you insert the CD into the Mac it mounts the Mac partition, not the PC partition.
Drop to the command line and figure out where the CD is getting mounted:
$ diskutil list
Make a temporary directory to mount the image:
$ mkdir /tmp/mnt
Mount the iso9660 partition at that location:
sudo mount -t cd9660 -o nodev,nosuid /dev/disk3s1 /tmp/mnt
Replace /dev/disk3s1 with your CD’s location.