Always use a new rubber, in fact the factory ones say "do not re-use" right on them. Out of the car it is easier but still pretty much easy even in the car. Correct size deep socket, 3" extension just to make it a little longer, a little silicone around the sensor, 16 oz ball pein hammer. Line everything up a smack it once with the hammer to install, reinforce with a zip tie and you are done. That is the sign of a good fitting sensor and seal, when you have to drive it in with a hammer.

Mark