The command to disable the graphical boot loader in the bcd store is:
Windows 8 installation media uses WinPE 4.0, which also uses the Windows 8 kernel and graphical boot loader, so in order to boot into Windows 8 or Windows 8 WinPE on affected hardware, you must disable the graphical boot loader in the BCD store of the boot media, as well as the target operating system that is deployed by Setup.
The simplest way to get the GUI (graphical user interface) boot loader disabled in WinPE is to copy the installation media to writeable media (such as a USB flash disk or USB hard disk) and edit the BCD store on the writeable media. It is also possible to (using the WAIK or OPK documentation), create custom media with this bcdedit workaround.
Once you successfully boot on the system into WinPE, you must also disable GUI boot in the target operating system deployed by Setup, which takes different steps to accomplish depending on which hardware you have. On a system with PS/2 keyboard, you may hold the left control key while the system is booting to bypass running Setup as the shell and instead go straight to a command prompt. You may then launch "Setup /noreboot" from the media, which will cause Setup to exit instead of rebooting the system. After Setup exits, you may locate the BCD store on the disk and use BCDedit to disable the graphical boot loader and then reboot to continue deployment.
If you have a USB keyboard, then after Setup reboots the system the first time, you must force the system to boot to the media again, click through the first two pages of Setup, and then press "shift-F10" on the keyboard to launch a command prompt, then locate the BCD store on the disk and use BCDedit to disable the graphical boot loader and then reboot to continue deployment.
In the scenario that you are performing upgrade from a downlevel operating system, you may run Setup from the command line with the /noreboot switch (which prevents Setup from rebooting when it is done), and then disable the graphical boot loader with bcdedit prior to rebooting.
Note that the path to the BCD store varies depending on whether the system uses traditional BIOS or EFI/UEFI. The known affected older motherboards are all legacy style BIOS systems. On a legacy BIOS system, the BCD store will usually be located on the System reserved Partition in the boot directory. On an EFI system, the BCD store is usually located on the EFI partition under the efi\microsoft\boot directory. Windows deployment media typically has a BCD store in both places so that the media will successfully boot in both cases. The BCD stores are separate for legacy BIOS and EFI scenarios, so you may need to edit both stores.