latest nVidia, latest Intel drivers and Restore Points
...My solution was to download the latest drivers for Intel HD 3000 graphics driver...
Not patient enough to wait for the rumored apple firmware or bootcamp release to address the Windows 8 x64 EFI audio issues on the retina MacBook Pro, I decided to update all Intel and Nvidia drivers.
The NVidia drivers installed fine. I can't tell if they help anything but nothing appears broken. They are the wHQL certified 1.11.3 update with 310.90 graphics driver and the 1.3.18.0 audio driver. I left two options unchecked, PhysiX and something else.
The Intel drivers however destroyed my system. I downloaded the 15.28.12.64.2932 x64 HD 4000 drivers in a winzip file from Intel. These are dated 19 Dec 2012. The install blue screened my computer and the machine's own attempts to restore itself were unsuccessful. I managed to get into safe mode, completely reinstall the drivers, reboot the still unbootable machine into safe mode, completely remove the drivers and then get a bootable system again. My rMBP crashed regardless of the use of "install Aero" option, which of course isn't supported in Windows 8 anyway. I was equally unsuccessful manually installing any of the intel drivers (inf files) onto the perpetually not starting "High Definition Audio Controller" on my system at "PCI bus 0, device 27, function 0", as none of the driver files showed as compatible.
I did not previously have a system restore point on my system. This may have made the attempted auto repair function faster and\or successful, so I would certainly recommend it for the adventurous.