1. installation

mkdir /boot/rip
wget -N -nv http://d01cid.ddns.net/sharel/pxe/rip/kernel64 -P /boot/rip/
wget -N -nv http://d01cid.ddns.net/sharel/pxe/rip/rootfs.cgz -P /boot/rip/

2. configuration

vi /etc/grub.d/40_custom
#!/bin/sh
exec tail -n +3 $0
#
menuentry "Rescue is Possible (RIP)" {
        set root="hd0,msdos2"
        linux /rip/kernel64 root=/dev/ram0 rw keymap=us autologin vga=711
        initrd /rip/rootfs.cgz
}
chmod +x /etc/grub.d/40_custom
grub2-mkconfig -o /boot/grub2/grub.cfg