I was running low on battery with my MiFi and I needed to charge it, but I didn't have an external USB/AC outlet adapter or even a plug for that matter with me. I did however have a MicroUSB to USB cable that fit the MiFi,but when I plugged it in to charge I could no longer use the MiFi as a Wireless hotspot and the MiFi was only seen as a local modem. That is great if you want to use it for yourself and charge, but its no fun for your family and friends that are used to sipping off of the Wi-Fi internet access you are always providing them with, which can eat through a MiFi battery right darn quick. What I wanted to continue to do was upload photos to my computer for direct viewing at a family event via my EyeFi card in real time and both were working well until the MiFi had run out of juice. So while drinking a beer I figured I would dabble with the configuration of the MiFi if possible.
I was able to charge the MiFi long enough while getting my beer and a something to nosh on to have it run as a Wi-Fi AP for a brief while I nosed around and was able to log onto the administration menu like a standard home router.
To Connect to your MiFi just type in 192.168.1.1 in your favorite browser and use the password is admin (I guessed at that so you may want to change that later to something else if you don't trust the people you are sharing your MiFi with.) Note you won't be able to access the admin screen unless you are connected to the MiFi via the password on the back of the device.
To reconfigure your MiFi click on Advanced->Config File and
choose download configuration file and remove the .sav file extenstion when you save it so it is just a .XML file.
Launch your favorite text/XML file editor - Notepad will do.
Change the routeroverusb value from a 0 (zero) to a 1 ->save it.
Next upload the modified file.
Restart your MiFi, now it won't act any different you can still connect to it via the Mobilink software that pops up when you plug it in, but you can now share your Wi-Fi connection and charge over USB at the same time. YAY!