The Core Configurator is a CodePlex project that can be used to administer Windows 2008 R2 Server Core installations.
It is completely open source so it can be amended and change to fit your requirements, this version has been a year in the making and has been written in powershell with a reference to Winforms so that a GUI format is displayed.
It’s a small application that you can either copy to the server or else run from a USB stick or network drive.
Get the great little tool here.