Wait, I see what you're talking about...

You're not having problems getting your computer to see the empeg's output...

Your problem is getting your little program that you've written that RUNS ON THE EMPEG to read the output FROM THE OXYGEN SENSOR device when both are installed into the car.

So the cables you're using... Are they custom cables you've made, or are they off the shelf things? I think the off the shelf cables might link certain pins on that device to lines you don't want them to. Pin 1 goes to phone mute and Pin 4 goes to amp remote (on the sled). Maybe those things are confusing the oxygen sensor device. Since pin 1 is supposed to be Carrier Detect and pin 4 is supposed to be Data Terminal Ready, I could see how this might happen.