It seems really easy to do. It's going to require a o2 sensor, and a a/f mix guage. Sensor is about 50 bucks, and the guage probalby another 50.
The hard part is welding a nut into the pipe to screw the o2 sensor in cuz you gotta take the pipes off, cut it, weld it, paint it, and put the boogers back on.
I think power commander makes a cool setup that has an o2 sensor and a few other things in it. It's also recordable so you can analize the numbers.