They've got you covered. If your kit came with the adapter (mine did) you're all set. Use some thread sealant on the threads. I put my OEM sensor into the adapter before I installed the adapter into the engine.
I needed a couple of shorty wrenches to get in there on mine since my exhaust was in the way. Remember these are pipe threads, forget about the torque wrench (unless you want to risk stripping your crankcase threads), and just tighten by feel. Pipe threads get tighter as you go (they are tapered).
Make a note of the position of the adapter when you START turning it into the crankcase. If then when you are trying to get the adaptor to turn back up so the oil line is heading up, you find it getting TOO tight. Then remove it and then start 180 degrees different than the last time.
Other than that it's an easy mod. I plugged the sensor hole with a clean rag to keep the oil from running everywhere.