Finally managed to install Windows 8.1 Enterprise on MBP2010.

Seriously? Accidently hit submit, edited my post to complete it and now everythings gone? Great!

So, for the second time - you can try and use gDISK to reroll to the protected MBR, then reinstall, fail at the end of the installation, fix the EFI, fix the BCD, resume the installation and fail again because the "hardware is incompatible"; I guess the Bootcamp EFI is still incompatible to the one Windows expects.

Means: no native EFI installation. At least for my hardware. I needed to install Windows on MBR, while booting into the EFI installer, because no other Setup would start. This meant installing Windows manually.

I needed to recreate the Bootcamp partition with the Assistant, then reboot into the Windows setup (DVD or flash shouldn't matter)

Hit Shift+F10 for the console.

Manually create the partition with diskpart:

dism /apply-image /imagefile:D:\sources\install.wim /index:1 /applydir:C:\

Notice: C is the newly formatted NTFS drive, D is the DVD/whatever.

After that's finished, write a new MBR and new Bootloader:

bootsect /nt60 C: /force /mbr

bcdboot C:\Windows /s C:

I guess you could also pick a language there, with /l de-DE or whatever.

Then reboot and hope for the best. Setup should continue from the hard drive and finish.

Since that's pretty much again (...) off the top of my head, I might've missed something.

I did install rEFIt before, but that should not be required for this to work.

Good luck!

Absolutely, but a) not everyone has a (working) internal drive or b) wants to use DVDs. I replaced mine years ago with an SSD.

Most tutorials work for some Macbooks, but clearly not all. This should be rather failsafe, albeit complex. Also, I don't think Apple lists the DVD drive to be internal as a requirement.

This could all be fixed by a few minor firmware upgrades, fixing bugs that are around for ages... but I'm afraid Apple simply doesn't care enough.

While it's not a far fetched assumption, I haven't found any official page stating this. It would be nice if the Boot Camp assistant would tell me that external DVD drives won't work, although it would be even nicer if it would just work.

Regarding the "hack": it's of course one of the first things I've done. But it wouldn't work on my machine; non-EFI boot seems to work ONLY off of the internal drives - flash drives are as external as usb opticals, and therefore don't work. Which is exactly why I posted my solution to the problem.

And I absolutely have to agree, the set of people is small and will get smaller. It would just be... nice. You know, to easily be able to install Windows on a three year old machine (via USB). Or to be able to install it at all (with no internal drive). While directly affecting only a small circle, it's portrayed image isn't exactly positive... but I'm starting to ramble. Anyway, maybe this helps somebody.