Again, I know this is a very old thread, but just in case someone reads this thread in the future,, here are a few tricks that I have learned during the process of changing my Crankshaft Sensor in my 2000 WJ.
By all means..... unbolt the cross member and lower the transmission.... this will provide the much needed space to reach the Crankshaft Sensor bolt with a long extention. I found that my bold was 11mm not 12mm as I had read. Also, once you have the bolt out and the sensor removed from the bellhousing, drop a single solid wire (about 3 foot) from engine compartment then tie it to the sensor..... raise the transmission to give you room between the rear of the engine and the firewall,,, then using your tied wire, fish the CS across the rear of the engine to the passenger side. The connector is at the base of the oil dip stick, like everything on a WJ, it's not a great loaction, but you will be able to deal with it. Fishing the CS across the rear of the engine doesn't sound like much, but it is not a "Fun" task. In a little while, I'll go out and start to put this Jeep back together, but I'm not looking forward to doing so.
I got my Jeep mostly back together, just a few odds & ends to button up. I have already had engine running which is a good sign. Getting the new sensor into the hole in bellhousing was not as easy as you would think, but that wire sure helped the process big time. The other thing that I did and it worked great was when I went to put the Crankshaft sensor bolt in, I put a little duct tape over the head of the bolt, then forced it into a socket, using the long extention, bolt went in like greased lightning.