This is the most frustrating issue I have come across.
I have twice now been able to get the Intel HD3000 active under EFI windows 8, and twice it has stopped working as soon as I try and get other device drivers running. This is a work in progress, brief post in case someone else wants to play as well. Assumes GPT disk, and macosx installed or recovered.
Install win 8 EFI (must use WinPE4 method, manually configuring boot. Win8 installer fails here every time)
Rename igd*.sys Intel HD3000 to stop blue screen. (either via macosx with NTFS write, or winpe4 USB)
I have had an external monitor connected.
Disable Intel HD3000.
Installed rEFInd and EFI shell.
In the EFI shell, I have issued combinations of these PCI register and I/Oport commands:
mm 0001013E 8 -pci (this is the PCI-PCI bridge, enables VGA)
mm 00020004 7 -pci (this is my SandyBridge HD3000, sets bus master)
mm 728 1 -io (as per metatechbe posts)
mm 710 1 -io
mm 740 2 -io
also tried
mm 00020050 2 -pci
mm 00020054 0b -w 1 -pci
Then exit EFI shell, then boot win8 EFI from rEFInd menu entry.
Rename the intel igd*.sys file back to original, and then enable the HD3000.
If it works, the screen goes black, thena few seconds later the display will come back and Intel HD3000 is Working Properly.
Rebooting you need to re-enter the EFI shell commands either via the EFI shell or an EFI .nsh script.
Get back into windows using Basic Display Driver
If I ever work out how to make this work properly I will do a how to, for now I will pull out some more hair and reboot the MBP another 100 times.
😐