According to my information the MAF signal wire is brown/blue. (your colors may be different) It is pin number 5 of the MAF connector. So the output signal from the MAF is connected to the variable resistor. The signal to the ECU can be adjusted. One more resistor is needed on the other
side of the variable resistor (10k ohm). It is connected to ground. (pin 3 of MAF connector
For best results you need a VAGCOM or similar. Measure the MAF with a TDI MAF and adjust the variable resistor such that the same value is read again with the 2.0L MAF. Also a simple voltage meter will do just fine: measure the output voltage of a TDI MAF and adjust the resistor such that the same voltage is read on the wire going to the ECU when the 2.0L MAF is hooked up. If everything is okay, the smoke should be gone, and the engine is just as powerful as it was with the TDI MAF. Only above 4000 RPM or so, a very small power loss may be experienced, but I don't think anyone will ever notice.
If you don't want to adjust anything, you can use fixed resistors. The picture below shows the same circuit with fixed resistors. The values should be about right for people experiencing smoke with the 2.0L MAF, but not with the TDI MAF. If the engine is still smoking with this circuit, increase the 820 ohm resistor to 1k ohm or even larger. If the engine starts to feel sluggish, the resistor is too large.