To try and keep a long story as short as possible:

I'm trying to install Win 10 on an external SSD, which I can boot on my MacBook Pro.

To complete the installation I have downloaded:
- install.esd and converted it to install.wim
- Windows 10 Pro ISO from Microsoft
- Boot Camp drivers from Apple

The final piece of the puzzle is to complete this step:

  • Windows AIK (free) running on your Virtual Machine or on your PC, or just the imagex.exe file (the rest of the Windows AIK package is not needed)

This is to complete this final stage of the installation:

Step 3: Deploy the Windows installation image

  1. Still using the command prompt in admin mode (you didn't close it, did you? ), locate the imagex.exe file mentioned in the "What you'll need" section and access its folder. In our example, we have put this file in C:\imagex\imagex.exe
  2. Your Windows installation ISO has probably several installation options in it. So in order to identify the right one, type in the following:imagex.exe /info C:\wim\install.wim
  3. Now identify the INDEX number of the installation that you wish to deploy. You will use it in the next step.
  4. Type the following and hit enter. Replace 1 with the INDEX you identified in the previous step. Also remember to replace o: with the letter you have chosen in the previous step:imagex.exe /apply C:\wim\install.wim 1 o:
    This will take some time. The Windows installation image is being deployed to your external drive
  5. Once done, type the following to create the boot section (remember to replace o: and b: with the letters you've chosen in the previous step):o:\windows\system32\bcdboot o:\windows /f ALL /s b:

    I'm doing this on a Toshiba Laptop running Windows 7.
    I've also purchased a genuine license for Windows 10 Pro.

    Any help greatly appreciated.