Here are a set of (hopefully) fool-proof instructions for those nMP owners interested in installing Windows 8, using Boot Camp and a Windows 8 DVD:
What you will need:
1) A Windows 8/8.1 DVD -
full version. Not upgrade.
I bought mine here. ***Note - there is at least one report that an upgrade version of Win 8 may suffice. See Ytoyoda's post further down this thread. If anyone else has a similar experience, please post.
2) An external storage device (USB thumb drive or portable Hard Drive) that is at least 500MB. It should be formatted to MS-DOS FAT. Disk Utility can format the drive to MS-DOS FAT if you need to do so.
3) Access to an external DVD Drive
To install Win 8/8.1 via Boot Camp:
1) Open Boot Camp Assistant. It's found in Applications/Utilities
2) There are three check boxes. Uncheck the first and check the second two boxes. You won't need to create installation disk. You already have a Win 8/8.1 DVD
3) Make sure your FAT-formated storage is plugged into your nMP
4) Click Continue - select the FAT-formatted drive as the destination for your Apple Windows Support software download (basically the boot camp installer and drivers for Windows 8/8.1 - about 431MB in total).
5) Once downloaded, you will need to enter your admin password to continue. This is a good time to pull the ethernet cable out of the back of your nMP. Doing this prevents Windows Update from starting until after you have installed bootcamp and the needed drivers for Windows 8/8.1. This is a good idea. Don't skip this step. If you're using wireless, don't log into your network from Windows until step 12
6) You will see a visual representation of your Windows and OSX partitions with dividing bar between them. Select your partition size by sliding/dragging the dividing bar to change from the default 20GB Windows partition. I selected 60GB (which translated to 56GB in Windows). My default Windows 8.1 install took up a little over 40GB after installing boot camp and windows updates. You may want to use a bigger partition if you plan to keep Windows 8 on your internal SSD - I did not, I used WinClone to move it to an external thunderbolt drive and then reclaimed the space on my internal SSD (note, this only works on external Thunderbolt drives - not USB).
7) Once the partition has been created by Boot Camp Assistant, your nMP will reboot.
Pay attention during reboot - a "Press any key to boot from your DVD" message will appear. When it does, press a key on your keyboard to make sure you boot from the Installation DVD. If you miss this, no problem, just reboot from OSX and hold down your "option" key during reboot and select the DVD Icon that represents your Windows Install DVD when prompted.
8) Windows installation will now begin - enter your license key - when you get to the screen that asks if you want to Upgrade or Custom install Windows, select the bottom option - you are not upgrading.
9) On the screen that follows, you
will have to format the partition that you created in bootcamp. The partition will be labeled "BootCamp". Select it -
make sure the boot camp partition is highlighted. Then select "Format" from the list of options below. This will NTFS-format the bootcamp partition and will allow you to click "Next" and continue.
10) Windows will install and then reboot. You will then be given a series of setup options to respond to and then Windows 8 will start.
11) After Windows 8 starts for the first time, if your like me, you will be lost (I've never used Win 8). You need to navigate to the external FAT-Formatted drive with the bootcamp software you downloaded earlier. To do this, click the "Down Arrow" icon in the lower left corner of the Windows 8 Screen. Then select - in the right column of Apps - "File Explorer". Navigate to the external drive, open the "BootCamp" folder and double click/run the "setup" file. This will install Apple's bootcamp utility and all of the Windows 8 drivers. You will be asked to reboot. Before doing so, plug back in the ethernet cable into the back of your nMP or log into your wireless network. It's ok to let Windows Update do its thing now.
12) Once rebooted, using the down arrow to get to your apps, select "control panel" then "System and Security" - from there, run Windows Update to update your Windows 8 install to current software, etc.
Other notes:
- To boot back to OSX from Windows, from the "Metro"/default Windows 8 screen, select "Desktop" or, click the "Down Arrow" to get to apps and select "Desktop" from there. From the Desktop, in the system tray (lower right corner) there is a small triangle icon. Click it and then click the grey diamond icon (Boot Camp). You will be given the option to restart in OSX. Or - just reboot and hold down the option key during reboot. This gives you the option to select from any "bootable" drives.
That should do it.