In case you have only access to (Linux) Rescue System, the proper install is still possible. Use qemu:
qemu-system-x86_64 -hda /dev/sda -hdb /dev/sdb -cdrom install52.iso -vnc localhost:0
Don't forget to tunnel tcp/5900 to your local machine for VNC access.
The only thing to mention: don't use disklabel(8) autoconfiguration, since it uses RAM size to determine the size of swap (256M + ramsize) and /var (4G + 2 × ramsize), which in case of using qemu will surely differ from the actual size of RAM .