You can use the same circuit as I designed for your C5.

Your MAF connector has 5 wires, the 1st 3 (Pink,Yellow and Black) wires are for the MAF.
The two dark wires at the other end of connector are the IAT sensor.
You would cut those two wires and then splice in the IATuner and it will work the same as on my '99.
If you have a PCM scanner, you could have it scanning with key on, have it show the IAT and as you adjust the IATuner resistor pot you can see the position of the pot knob what the IA via the scanner.
Mark the pot knob at the different temp readings of scanner so now all you have to do is turn pot knob to a mark and know what the IAT value is.

John