You can use just about any IAT and CLT sensors that you want, using the EasyTherm sensor calibration program which adjusts the firmware in the MS to accept any sensor. This means you can use the stock sensors as long as you properly calibrate the setup and disconnect the stock ECU from them first.

In theory, you can share the stock sensors with the stock ECU still hooked up to them, but supposedly the stock ECU changes the bias resistor internally in order to promote accuracy over the entire range which makes sharing impossible :(

Most people use the GM coolant and intake temperature sensors. Part numbers can be found all over MSEFI.com and megasquirt.info.