Make sure to run your command prompt as administrator for these commands to work.
netsh interface 6to4 set state disabled netsh interface teredo set state disabled netsh interface isatap set state disabled References http://directaccess.richardhicks.com/category/windows-8-1/
This enables the Windows version chooser during install.
Edit ei.cfg in the sources directory to read:
[Channel] Retail Testing this with a Windows 7 Ultimate ISO gave the option to install Basic/Premium/Professional/Ultimate. Of course, you will need a different product key to install the versions you did not pay for. This only unlocks the ability to install other versions.