Do yourself a favor. Start with a magnifying glass so as not to kill it, and then once it's out, quadruple the time and narcoberries necessey to keep it unconscious. Calculator is really off when it comes to dinos whose torpor rapidly drops.
To tame one of these just clear out an area of all other creatures. Then eat a rare flower so it will agro you. Shoot it with a few darts and boom it’s nocked out. Make sure you have lots of narcotics though.