[Libguestfs] virt-v2v / virt-p2v

Hi all, Trying to figure out how virt-p2v works to convert an ubuntu. First, I do not understand why do I need an ISO image to make it run ? Can you explain me quickly ? Can't I directly use your source tarballs ? Having a look in my RHN account, redhat6.3 is not out so no ISO to download yet. By the way, the provided link http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Virtual... is 404. Thank you for your help.