Learn Death Metal Vocals?

Now, I am an older man (56), but it has been my lifelong dream to be able to sing along with some of my heroes (Frank Sinatra, Nat King Cole, Cannibal Corpse). Now that I have some time on my hands, I'd like to learn to sing beautifully to songs by Opeth, Lamb of God, Whitechapel, Duran Duran, and the aforementioned Cannibal Corpse. Can someone give an old guy a place to start?