Hi Norbi ! Did you succeed in installing 10.7 or 10.8 ?
I have a x301a, almost the same as your x401,
I can boot to unibeast usb, setup ML, reboot to usb and choose installed ML
finish install, run multibeast and set chimera up.
But then asus uefi bios doesn't see chimera bootloader : no boot options appears.
So I'm stuck there....
Any clue ?