I can't help you there, but wondering if simply placing a resistor on the MAF would lower voltage enough to force the lower voltage to the ECU? I'd start with a 1k resistor - which you can get anywhere...or even a variable potentiometer (Radio Shack) with a 10ohm-20k ohm spec. You will find the voltage you need in there; I'm sure. Just dial it in until you get what you need. All the MaFIA does is lower the MAF output voltage to the ECM, no? The potentiometer would do exactly the same thing...
With a cheap voltmeter (Radio Shack or Home Depot), you can figure out where the pot needs to be set to NOT exceed 5 volts, or whatever max voltage the ECM needs to see. I think that would work for you. With the potentiometer I posted about above, output voltage becomes fully adjustable. The output voltage would still be as linear as the MAF itself and this should all work. Any port in a storm!