USB Flash Drive Help

I read once, a while ago on www.trilliananywhere.com, that there was a way for you to put a file on your flash drive, i think it was "autorun.ini" and then put a line in there that made any computer you plugged the flash drive into assign a certain drive letter to the usb drive. Right now windows is trying to assign it the letter "F:\" but i want it to be something different like M:\. How do i make it so no matter what computer i put it on it is assigned to that letter?

 

*bump*

someone plz help!

 

The auto run thing can be done but as far as making different machines assign the same drive letter I don't believe its possible.