Added a valid OEM SLP key for Windows Server 2012 R2 Standard (it was taken from a Dell server) Added a warning for virtual machines created in VirtualBox that are using Windows Server 2012 or 2012 R2 (use ICH9 for the loader to work)
Just make sure you remove all USB flash drives before you use the command. Alternatively try holding the 'R' key after your BIOS screen. If you time it right then you'll see a boot menu.