So your current switch has only three wires from the car connected to it? Is the 4th wire not hiding behind the dash somewhere?
Or, maybe the non-OEM switch was wired up seperately, so you might have the proper connector hiding in there somewhere ready to plug straight in?

As for the 4 wires, two will be for the light inside the switch, and the other 2 for turning the fogs themselves on, but I couldn't say which ones are which without taking the dash off, if no one can tell you before I next do (might be tomorrow) then I'll get the multimeter out and find out for you
