The Windows Offline Configurator is fully compatible with the new CTP3 version of Windows Embedded Standard 8. However you will need to download the new package to get the new license file to run build images for the CTP3.

With Windows Offline Configurator you can build Windows Embedded Standard 7,Windows Embedded POSReady 7 and Windows Embedded Standard 8 images offline on your fast development machine.
The tool allows you advanced configuration, such as creating the user, password, time zone, etc. The resulting image will not require you to go through OOBE as everything can be configured within the tool.
You can even create a VHD file and build the image into this file for easy deployment!