Found it, thanks for the great info. I took a picture to help anyone else who may need it.
This worked on my '07 Subaru Impreza WRX (Turboed Model)
The ECU is in the kick plate of the passenger side.
1. Pull back carpet from under dash. (3 plastic screws towards top)
2. Remove the 3 bolts holding the metal plate
3. Remove 2 bolts, one towards top, one towards bottom, holding the ECU in place.
4. 3rd plug, green wire with yellow tracer is your guy. See picture.