This page describes the so-called "RouteOverUSB" hack for the Novatel MiFi 2200 WiFi 3G router.
Notice: This hack no longer works, thanks to a recent MiFi firmware update. Please see other solutions below.
If you know of another workaround for this, please contact me (wilsontp at gmail.com) and I'll include that information here.
Background
The MiFi router is a great tool for getting Internet access for up to 5 computers (or mobile devices) on the road. However, it has a glaring weakness: you cannot plug it in to a computer to charge and use the wireless server at the same time. (You can, however, charge it with a wall or car charger.)
Apparently, this functionality was disabled because the combination of charging a LiPo battery, and powering the WiFi and 3G data radios is just a bit too much for a plain old USB port.
The Fix
However, you can turn this function on manually. Here's how.
Unplug your MiFi from your computer (you can plug it in to the wall charger, if necessary.)
Download the configuration file
Edit the RouteOverUSB section
Set the value to 1 to enable the radio while tethered
Set the value to 0 to turn it back off.
Upload the config file back to your MiFi
(note, I will be adding detail later... when I can turn on my MiFi and fiddle with it.)
After you plug the MiFi in to your computer, the WiFi will be available. Note that you can't actually use the VZAccess program while running the wireless server; you have to either disconnect the wireless connection first or connect to the MiFi with your computer's wireless connection (even though it's plugged in to the USB port.) I think this is because the VZAccess program takes over the 3G modem, preventing the internal router from communicating with it.
Side Effects
Your MiFi will not charge properly off the computer's USB port with this hack enabled. The battery may not charge at all, or it may charge very slowly. The diagnostics page on mine gives me sporatic readings, and so I only enable this hack when I think I'll actually need it.
Other Solutions
Despite the lack of software support for charging and operating the MiFi at the same time, it's sill possible to do it with a special USB Charge-only cable. You can find charge-only cables in some USB battery packs, such as the Energizer "Energi To Go" pack (check out http://www.xpalpower.com for more details.) You can also open up a USB cable and cut the data leads, leaving the black and red power leads intact. Regardless, you should be using the MiFi with a 750mA (or higher) charger in order to ensure that the MiFi is getting enough current to actually charge the battery while operating. When running from a PC USB port, the MiFi doesn't actually get enough current from the USB port to charge while transferring data.
Disclaimers
If this breaks your MiFi, don't blame me. You're doing this at your own risk. This may violate the warranty, may cause global warming, or may kill baby bunnies.
Contact
If you found this trick helpful, let me know. My e-mail address is wilsontp (at) gmail (dot) com.