Yeah its not to difficult.
All you need is a 12 volt power supply, a fan and a multimetter.
Hook the power supply positive to pin 5 and the negative to pin 3.
Now hook the multimeter positive lead to pin 2 and the ground lead to pin 4.
You should once power is put the the afm see a voltage of around 0.5volts with no air flow.
Now turn on the fan and see if the voltage increases to around 2.5 volts.
This could be more or less depending on how much air the fan will blow.
A variable speed fan is best as it allows you to test the afm at different levels of air flow (more air more voltage).
The pin out of the afm is the same as the RB20 unit so if you get confused have a look at http://rb20det.com/air_flow_meter_pinout.html
Hope this helps