Yo my man, if you are still trying the O2 sensor swap, place a wrench on the sensor with the end pointing up at about 1-2o'clock. Slip a piece of pipe(gal. but PVC should do) 1.5-2.0" dia. and 3' in length over the wrench, from above, and pull towards the driver's side, sensor should come loose easily and you can take it out from below with some difficulty and cool profanity. Install the new one from below.
Good luck, god speed, and have lots of spirits nearby.
dr. Majik