auto to manual swap

I need help on swapping out my tranny for a manual tranny. I know the parts that I need, but what about the ECU? Do I need to change it? I knoe that there is an entire plug in the ECU that's responsible for the operation of the auto tranny. If I have to change the ECU, does that mean I have to change the wiring harness as well? Than the last thing would be about getting the ignition lock out that works with the auto tranny. How do I go about that?