The method I used to tame was picking up the beaver with my crystal wyvern and dropping it in a taming pen. Pretty easy knockouts but their torpor drop rate is INSANITY and you can't leave then for more than 3 minutes. Feed them either mejoberries or crops (kibble is really expensive but if you want to do that, go for it).
Not sure why everyone discourages taming. I'm pretty sure the game replenishes their numbers every time the server goes through a wild dino wipe, and these little guys are really handy to have around for what little space they require.