Go with a fly mount and leave it near him, you have to follow the calicho standing behind him and feed him when he stop for make shit or for change direction to be not attacked. If he attack you take the fly mount and a bit over him until he don't attack you anymore then go back to feed him.
For beginners these things will spot you in a split of a second so don’t even think of going up to it with a stimberry in your hot bar. Instead, get a ghille suit and sneak behind it and feed it a beer! Don’t use stimberries it is pain And time consuming unless you have a bush of stimberries. They eat berries after they are tamed though. Not beer.