i've watched the video of dime explaining the technique for doing the guitar squeals by grabbing natural harmonics when the bar is dived. But I see not just dime, satriani, but even am's making videos that show them doing it somewhat clean. They flick the 3rd fret of the G string, grab it and pull that bitch back and it will wail for a long time. When i pull a harmonic and make it wail, i get it the majority of the time, not all the time but. Question is, how the hell can you make it sound clean with out that Ping sound of flicking the string? Or is it just natural?
It's mainly practice, but it also has a lot to do with technique. What I mean by that is by attempting to do it a lot you will eventually figure out exactly what works for your fingers and the way you are accustomed to holding the pick. After you've put your finger, so to speak, on what it takes you to make it squeal like that a good few times in a row, simply repeat that and refine every exact nuance of your hands, and eventually you will be able to make it squeal like that effortlessly, without even putting any more thought into it than you would a hammer on or what have you.
You have to do it very quickly to get rid of the "boowow". Getting it clean every time just takes practice. Be sure to keep the other strings muted very well. Gain high Treble help as well, so does using the bridge pickup.