[KnightmareCS]

I don't see why this so hard. You already can tell if you're in lean burn by monitoring whatever voltage to see if it goes positive. Why can't you use the same pins and run a wire from them to a circuit which relays a LED when the voltage is positive or whatever range? You can use a pot to fine tune the lean burn range light up. I'll ask my friend what he would suggest, but it seems like a straightforward doing.