if you mean the pinch harmonic (adding thumb to pick attack) , you should try different picking spots (some will work , other won't) , memorize them by their position from your pickups... (there are theories for this, changing the pitch of the harmonic and stuff like that, but having the pickups as your landmarks is the easiest way of learning them)

actualy the word artificial harmonics has a lot of meanings , so if what I explained isn't what you want , check out the artificial harmonics link at Guitar tricks home page, it will help.