Does anyone have hints on troubleshooting Personal Hotspot with Lion on an Air over USB?

The existing KB article on troubleshooting an USB connection to a Mac makes no sense to me on Lion with my MacBook Air.

It says to mark the ethernet connection inactive. I've got the Wi-Fi and the iPad network connections and marking either inactive and then active has no effect on the USB tethering.

The iPad entry says cable disconnected even when my iPad is connected. iTunes starts and can sync to the iPad and tethering works over bluetooth or Wi-Fi, but I'd like to get USB tethering working so I can shut off my Air's radios completely and tether to my iPad 3.