Hey guys how about this dohicky.

http://www.ecycle.com/buckboost.html

 

You won't like the price on it.

I don't know where we are either.

 

What I mean by EIFE is either (like Sgt Wookie stated) just switch between the two channels using a relay or semiconductor analog switch, such as a CMOS 4066 (Maxim/Dallas has much better analog switches)
or (poss and)
build a comparator circuit with a pot to adjust the threshold. Something like a pair of LM3914 dot-bar LED drivers would be beneficial to view what your threshold setting is and the actual output from the wideband O2 sensor. (also suggested by Sgt Wookie) This would be used on the wire that does not emulate the output of a narrowband O2 sensor.

I could just buy the digital gauge from innovatemotorsports.com like the XD-16 to show needed info
http://www.innovatemotorsports.com/products/xd16.php

So all I would need to do is build a setup using a relay or semiconductor analog switch, such as a CMOS 4066. Could someone help me in this endeavor?