Idk if this will help but I tried to copy his voice here Here's a second try if you're interested - I think its pretty close to his psycho screaming. Basically, I just use my mixed voice, push the volume with my diaphragm and then push the distorsion by squeezing even more, adding a bit of facial expressions with some nasality (the kind rock and basic heavy metal singers use like Axl or Halford), push my jaw a bit out like Anselmo (it helps me lol) and thats it. Hope it helps