Try an EFIE. You could Google search "EFIE". Should be some on the first page that comes up. ElectoronicFuelInjectionEnhancer (EFIE). Works good with those Hydroxy boosters everyone is talking about....
From what I know, some O2 sensors works on 0.7-3v? with a working current of 0-416uA. So, if you can build a circuit that can put out those parameters your ECM will think you have a real O2 sensor....