The REAL username/password to USGX-8810-B467-233PX.com has been found by Unfiction's Tether!
The password was in fact something that Alyse Hanssen should have been able to figure out herself, IF she bought the Cloverfield DVD (and not the SteelBook version!!).
The username is simply alysehanssen, and the password was the mysterious number on the "Project Cloverfield" sticker which seals the DVD - 11112014349.
Entering the correct username and password reveals no new information, and the "parent directory" still takes you to "unauthorized", so I have the feeling we have found everything there is to find. Good work everyone!
* Thanks again to Tether for figuring it out, and to Kenneth and Adrian for emailing me! You will all receive a copy of my limited-edition CloverfieldClues DVD!