this dosent seem hard in any way (if you are a programmer, or engineer). You could design a small antenna that fits into the bottom usb port, and when you are in a location with an EDGE or 3G signal (which is almost everywhere I think), you could just tether onto that signal. I dont know how cell phone signals work but wouldnt it be pretty easy, i mean, if you can get wi-fi from your house, shouldnt you be able to pick up another signal in the air, from another antenna on your iPod?
And, is it possible to get free 3G or EDGE on an iPhone by any chance???
cuz that would be easier than making an antenna for the iPod Touch.