I am also a wildfire user. I did so many searching for reverse usb tethering, what I searched for were similar to the script of this thread. I follow all the steps but also not success.
I did do some searching, I just GUESS the main problem is the router at my home. My computer access the modem via router, maybe the router cannot give my WF a IP so my WF cannot access the internet? I dunno.
I didn't try access the internet with my computer connecting directly via modem without router since my home wire connection is so so so so complicated, but I believe that it will success. Would somebody try it and share your experience?