I normally dont like when people post the same thread on 2-3 different forums, but i've seen this question asked many times on all forums so here is the solution that is working for me.
I tried 3 different versions of this. Finally one worked. 2) 2" PVC Plugs, 1) PVC Coupler, and some primer/cement. Oh and a screw on valve stem that discount tire gave me for free.
Theres a tiny little screw from the sensor to the valve stem. I took that off, removed the valve stem and then reconnected that screw. Not sure if this is important or what but i didnt want to take the chance. I just bent the wire so the valve stem was in line with the sensor so it'd fit in my 2" compartment.
According to some Lexus forums they put in some "stuffing" from an old plow to keep it from rattling around. I was concerned bout rattling but if nothing else it kept the cement from getting all over the tpms sensor. Some on the Lexus forum said they couldnt get it to seal up. I think the key may have been time. Since my tranny was being worked on it had plenty of time to dry. I think the most important thing i did to get it dry was to remove the shrader valve. Once sealed up the cement on the inside has no way of drying up. I took a lighter to the valve and the fumes would just burn like it was a candle even a day later. So i took a can of compressed air and would occasionally stick the tube down the valve and get some fresh air in there. Also about 3 times i put a extra coat of cement on the outside which didnt take long at all to dry. I then aired it up and put it in the sink. No bubbles!
Tranny was done last night so i threw the sensor in the back. It didnt work at first, but by the end of the night i realized i could see the temp/direction again without pushing a button! Id guess i went about 15 miles before it turned on.
Sorry i didnt take more pics on the process, just the finished product. Fits nicely in the back and that velcro is a great little mount