pinched harmonics

Hey yall, i got this major problem here.. See, i wanna be able to do those freakin cool harmonic squeals like pinched harmonics that zakk wylde and my all time fav, dimebag darrell(R.I.P) were the absolute gods of...
i've tried the various recommended techniques like only allowing da barest hint of the tip of my pick to protrude and digging into the strings hard so dat the string bounces of the pick into my thumb, but still no squeals!!..
i've tried the 'hotspots', ie... 3rd, 7th and 12th frets but still nothin...

could it be the settings of my amp?? i heard using alot of gain and volume as well as reverb help, but all i get is a hell of a racket esp when i turn the gain up, i'd prob go deaf in 3 seconds. little help from anyone??