Going through the wheel well is the best way. Remove the liner like Trainmaster said. Also remove the nut so that the transmission dipstick can be pulled aside. Try to hook the connector and pull it closer to the wheel well area and get it disconnected. Get the O2 out. I was able to break it loose from under the vehicle, then unscrew it the rest of the way by hand through the wheel well. Hand tighten the new sensor through the wheel well, go back under to tighten with the with the wrench, then reconnect the sensor through the wheel well making sure the wire is clear of the exhaust. I've done the job twice. Second time was able to do it very quickly using this approach.
