OK, I got your PM, but I had to come back here anyway to check what stuff you have...

The wires on a 4-wire O2 sensor are for:
1) O2 sensor signal
2) O2 sensor ground
3) +12v supply from main relay, or from ANYWHERE that's live
4) heater circuit ground side - the ECM closes this to ground when it wants to turn on the heater.

I don't know which terminal on your ECM. You'll have to get a circuit drawing (Helm book?) for the car your ECM came from. I wouldn't trust that it's the same for all different years/cars. So I guess I can't REALLY answer your question. The heater circuit (#4 in my list) is A6 (orange/black) in my '95 GS-R. The sensor signal is D14 (white/red). But I'm not confident it's the same for different years.