The wiring is easy but there are 2 types of TPS and one is wired exactly opposite the other. Just wire it up and then watch it in megatune. if the TPS comes on at 80% o-pen and then goes down just swap the wires around. I wired mine as suggested and then had to reverse it. There is a marker on the connection side of the SAAB TPS, 1 = green w/red, 2 = black w/white, 3 = grey. they are wired like this (or the reverse)

TPS                MS DB37 connector

3-----------------DB 22 (TPS signal)

2----------------Ground

1----------------DB 26 v-ref

here it is from the side

I just wanted to add some pics of the traditional mercedes TPS which is actually a mechanical switch so you can see why it is necessary to change to a potentiometer type switch. below are the original switch from the 107 mercedes in the middle, one from an early saab on the left and the later saab on the right

The mercedes original and the saab early  (both or which have adjustment ears on the sides are mechanical switches and are no good for the MS system. the later saab is a potentiometer and you can tell the case as there are 2 set holes and it cannot be adjusted. It also looks totally different to the early type but you would be surprised at how many people have emailed me to ask what the difference is!