The throttle position sensor has two mounting screws to remove and then it will rotate 15 degrees counterclockwise. Just remove the last screw slowly and hold on to the sensor. Then when you put the new sensor on, it goes back on in the exact same 15 degree counterclockwise turn and then you turn it back clockwise to line up with the mounting holes. Basically that is the torqueing process. I read some postings that on other Lexus models you have to calibrate/adjust the sensor mounting position, but the RX mounting holes are fixed, no way to adjust. The sensor is keyed so that it can only go on 2 ways, the right way, and 180 degrees the other way and the holes don't line up that way.
I throttle post (whatever it is that pushes inside the sensor) is spring loaded, so when you push the sensor on and turn it clockwise to line up the mounting holes that is the torquing that you are referring to.
I don't have the number handy, I just picked it up from AutoZone.. It was a Wells name brand around 50 bucks. They did list another brand for 34, but were out of stock. $50 was still better with maybe a whole 15 mintues my time then taking to the dealer.