what I think that post is describing is how to boot from an ISO, because they may have forgotton to insert the disk via the UI before first boot.
the VM, by default on first boot, will try to boot from CD ... but any subsequent power on it'll boot from hard drive.
what he's describing is how to get the system to reboot from a bios screen to the inserted disk.
the mention of network is because it's failing at the PXE boot screen.
but now that I mention it, you could setup a PXE boot system to do your installation assuming that your VM can reach the PXE/TFTP server.