See, pinch harmonics ARE artificial harmonics. You know how you get those artificial harmonics most commonly at the third, fifth and seventh frets? Well you can get them all over the fretboard, even off the fretboard above the pickups. So knowing this, it's just a matter of picking a string and simultaneously performing an artificial harmonic on it. A lot of distortion helps. You should attack the string sharply, and use the edge of your thumb to sound the harmonic.