I have recently downloaded and installed Windows 8 from Microsoft MSDN. While playing with it, I thought of the new WinPE 4.0 (WinPE = Windows Preinstallation Environment) and started doing some research. While, there are not many Winbuilder projects out yet to support it, I found set of instructions at Reboot.Pro

There are more packages than what is listed in the article, should you wish to do so. I tried it and worked great. Now I am playing with some antivirus tools to see which one would work under WinPE 4.0