If you're running a single turbo setup and not the stock twins, you can modify the upper water pipe to accept a sensor (or two). I have one that I modified with two 1/8NPT bungs in place of the stock nipples (one's plugged, the other for the sensor)...it's polished and looks great.
If you're interested in saving time with that approach, let me know -- I'm selling this one as I've already modified a second one for a slightly different project I'm doing now.
If you've got a metal upper radiator pipe, you could modify that. If not, you'll probably have to use the metal pipe that comes out of the block that already has the two stock water temp sensors in it.
Do a search, there was a post from Axoman about this.
The BLITZ® Cooling Performer is constructed out of 2 ply silicone and was designed to replace the upper radiator hose of specific vehicles. The Cooling performer also an additional tap to simplify the installation of a water temperature gauge.