I tried and failed for years. A friend of mine tried to show me on my cheap first guitar and said he couldn't do it because there was not enough gain, he was only using an overdrive pedal. Now I have lots of guitars. I find that some are super easy to get the pinch harmonic, it is just finding the right spot to get the right pitch. Still can't get them from that original guitar, regardless of the distortion and I have various degrees of luck on other guitars.
I think a big part of it is the pickups and maybe the guitars ability to produce the higher harmonics. Maybe something to experiment with next time I change pickups. I built a guitar with an alder body, maple cap and neck, Pau ferro fingerboard, and put Bill Lawrence lx500 pickups in it. It squeals like a pig when I want it to.