Create a CDROM Image with Context Packages 5.10 Docs

I don’t understand what the docs mean in the section " Adding Content to Your Cloud" under the “Step 4. Create a CDROM Image with Context Packages” section. It has you run the genisoimage command to create the iso package with the context packages, but what does it mean in the next section where you run a script that runs “mount LABEL=PACKAGES /tmp/mount”? An ISO is read-only, so what do they mean as far as mounting it so you can install the context packages? What does it mean about mounting LABEL=PACKAGES? Thanks for any help anyone can give me.