I just set this up for my mom, so I thought it might be interesting for others too.
Anyway, here’s the process of scanning multiple page documents in Windows 8.1 Preview.
Once the scanner’s driver is installed and the Scan app is present, simply click on it in the Start Screen. When it opens the UI should look something like this:
You can click ‘preview’ and the scanner will send you an image of what the document will look like.
But you can select other options, like XPS for file format (which will create a multi-page document), Greyscale (appropriate if you’re working with text, and other options)
And then it will save in your Documents folder! Voila!