Well you will have to infer the formula from a couple of data points and then try to use some logic to dial it in. What I mean is if you put the raw PID in Torque what value does it give you? Most likely you will just need the A * B variables so I would start with =(A*256)+B
That will give you some number - what I would do is assume that your car is trying to reach stoich (which is going to vary depending on the car) but I believe the Taurus like to try and hit 14.1:1 on E10 or so...
So you take the raw decimal number the equation gave you below - let's pretend the above non scaled formula in Torque gives you a value of roughly 1800. Well if you are sitting at idle (and there isn't an emission test or something going on) you "should" be seeing 14.1 on the gauge...so simply divide 1800/14.1 = 127.65...now since the ECU is binary/hex based it likes to use numbers that typically use a base 2 math system. That's a fancy way of saying the number is "usually" a 2,4,8,32,64,128,256,512,1024,...and so on. Not always though. If you are lucky you would simply look at the 127.65 and realize the actual number is probably 128...so your formula would just be:
=((A*256)+B)/128
Make any sense? It's sort of a trial and error thing but you should be able to get close with a reasonable degree of accuracy given that it will most likely be a linear formula. You will obviously have to use your own real world numbers to see if you can figure it out. Good luck! Feel free to post your values here if you want more help.