Windows 8 and Server 2012 have an annoying default installation process which forces you to enter a product key during installation. Often you may want to paste this in later, or just not enter one if you are installing a demo or test system, having to type one in manually is a massive pain. Luckily, you can easily modify the installation so that it lets you skip the requirement for entering the product key. The easiest way to do this is by creating the ei.cfg file in Sources folder in your ISO or USB media.
For Windows 8 or Server 2012 – this is the file that I normally create using notepad and save as ei.cfg in the Sources folder.
This works using MSDN or Technet (RIP) keys and media. I don’t bother entering the version, since I often may want to choose that during installation. By not entering the version you can choose if you want Standard, Datacentre etc.The format of the ei.cfg is as follows:
[EditionID]: This is the version of Windows that you want to install. This varies by OS. You can use Dism /Get-ImageInfo and specify the image file to get the editions available from the wim file e.g. Dism /Get-ImageInfo /imagefile:I:\sources\install.wimValid options are:
[Channel]: This can be OEM or RETAIL depending on the type of media that you have.
[VL]: This can be 1 for Volume License, or 0 for Retail
See http://technet.microsoft.com/en-us/library/hh824952.aspx for more information.