installing a scanner over a network.

You might be able to manage it all with Image Capture. If you go into Image Capture and select that you wish to share your image capture devices, and then open image capture on other computers that you want to scan from, and find shared devices, you should be able to scan across the network though.

From what I can tell from HP's website, you need to be running the software that came on the CD along with the printer (also available here)to be able to do anything but print. The distinction between selection "Networked" and "Local" is also important during the setup of the printer (though you can change it in the configuration panel). "Networked" will open up more connection options, needed to be able to scan properly with the software.