I think you misunderstood. In what I'm envisioning users would not need to type in a MAC address. The infrastructure would detect the new device (via MAC and/

I think you misunderstood. In what I'm envisioning users would not need to type in a MAC address. The infrastructure would detect the new device (via MAC and/or other fingerprintable characteristics) and tie it to the user based on time (here are devices plugged in recently), location (filter by devices in jacks or access points we think are assigned to / proximate to you), and their input (yeah that guy is mine!). You could have them disconnect/connect the device a small, specific # of times to confirm, if there's too much ambiguity (lots of similar new devices just plugged in).