I downloaded Open Garden from the market. Put it on the rooted TB (yes, TB must be rooted).
Turn both wi-fi and 4G on, and start the app. Click the big wi-fi icon in the center.
Have the Tab scan for the SSID noted in the Open Garden setting (curiously called OpenGarden for ease)
Boom... Done.
I ran it again this morning to download a free app from Amazon Market.
Granted this isn't a "hard wire" solution as mentioned by the OP, but it works really well. I like it because when I am in the field using my Tab, the phone can be on my belt without worring about a cable getting unplugged as I move around.
Also, with a cable solution, don't you need to buy the adapter which plugs into the Tab that will allow you to connect a standard USB to micro USB cable t0o connect to the TB?