The only schematic's I have are from the PET diagrams or
http://www.the944.com/files/951digit.pdf . I am trying to map it out the best I can just to gain knowledge about it since mine whacked out, regardless of exact part match, an electronic theory type of thing. Outback & another guy gave me some feedback that knocked one of the "why didn't I think about that?" bells in my head when they mentioned the ignition timing and fuel injectors.
I don't know of any tools that may be used. That plastic top looks like it would break fairly easily with a lot of pressure twisting it on opposite ends, and even "wide" {16 Metric} pressure evenly applied on each side would most likely crush it and leave the magnet like you stated earlier.
See if you can use a tube like those on the 10W-40 cans and spray the PB as close as you can directly down on that "O" ring. It may be stopping the lube because the crap underneath has formed a tight bond.
Another thing you might try is using high pressure air like one of those cans you would use to blow out a computer. It would create a lot more force and push the lube down without having a gallon of lube sprayed all over the top of the sensor.
You don't have a lot of options if you are having to turn it with the pliers. Of coarse you know that since you have already taken the other sensor out. When I took mine out it took a long time while I was killing my knees and trying to turn the sensor. If you can get it to turn with your hand that will be a good sign and it shouldn't take much more force to get it out.