Updated 2012/Nov/6 - Give a nice thanks on the blog if this helps. Thanks :)
Only hardware version less than 1.3. Read at end for versions 1.3 and greater.
This will automatically unlock your MiFi. No need for tools like dc-unlocker or the Novatel sim unlock tool.
Be sure and take any SIM/microSD out while flashing it..
# made with checksum.. point-and-click hashing for windows.
# from corz.org.. http://corz.org/windows/software/checksum/
*The default Wifi Password is 12345
*The default login pasword is admin
*AT&T DATA ONLY SIM uses the apn
no username/password or auth.
*AT&T 3G / HSUPA
I had to go to internet -> settings -> network technology -> 3G -> apply and then battery pull to get the card to recognize 3G.
iPhone had 3G so I had just battery pulled it, but it came back up with the same issue. So I forced the MiFi with the above instructions and all is well now.
The card is getting about .25Mbps more than with AT&T firmware, on a continuous basis.
*Secondary unlock method
pastebin version: http://pastebin.com/TpL4fMKN
The coveted iso no one can find:
http://preview.tinyurl.com/novateliso1 [backup - don't use unless the first one doesn't work and also let me know]
Email me jason.sands @ the-regular-gmail-com-domain and I will attempt to help you. Contact a tech friend for face-to-face help first if you don't know what 7z, zip, iso, and/or sha1 are.