legatos are usually just single string runs that use very little/no picking. (hammering on and pulling off, essentially.) and um, not to sound close-minded, but why the hell do you want to play artificial harmonics on an acoustic? a better and cooler acoustic technique is something like a slap harmonic, where you play a chord and karate-chop the notes your playing 12 frets above; it gives it a real cool bell sound like a natural harmonic, but you can play it in any position.


btw, i just learned a really sick song by donovan frankenreiter called "butterfly" a few minutes ago. that will rid you of any desire to play metal guitar on an acoustic.