Create KVM guest with .iso installer attached as cdrom fro package repositry

When installing via the terminal with virt-install ensure that the disk option has the --type=cdrom added to it.

--disk          /home/alex/jigdo/debian-12.5.0-amd64-STICK16GB-1.iso,device=cdrom

This should appear as a block device, potentially sr0 where it can then be mounted into /media/cdrom and then added to /etc/apt/sources.list with the use of the apt-cdrom add command.