There is a really valuable blog post on the Hey Scripting Guy! blog that explains how to install and configure WSUS on Windows Server 2012 using PowerShell. Enjoy!
P.S. we're looking at improving our own PowerShell coverage in WSUS in the future as part of our work towards compliance with Microsoft's Common Engineering Criteria. If there are scenarios you find particularly painful or just missing, please let us know in the comments below. We'll consider and respond to every piece of feedback!