Check out these tabs. It includes hammer on's and pull off's but I see a lot of covers for that song on youtube that don't use 'em. They just pick.
Plus I don't know if the original song uses 'em either. How do you figure hammer on's and pull off's in a song?
And where did hammer on's and pull off's come from? Why do you have to use them, why not just pick? Do they make any difference in a song?