<p>Run SCONFIG. Just type sconfig at the command prompt. Then choose option 6 or 7 (the exact option escapes me at the moment) for Windows Updates. You can change your Windows Update settings to install updates automatically, or you can download and install them manually, just like with the GUI.</p>
<p>sconfig comes with Server Core out of the box. In fact I think it runs at startup the first time you log on to the machine. Not sure how you missed it… maybe it doesn’t run at startup on Hyper-V Server 2012.</p>