To tame these easily make a pin. It can even be made of thatch! Put one foundation down. On one side place door frame then walls on either side making it two high. Put a hatch frame on top with a ladder on side of walls. Agro it to chase you inside the box. Then put walls all the was around even replace the door frame. He can not see you anymore so he'll loose agro. You will have to replace the walls he's attacking to trick him into loosing agro. Then just lay down on the hatch frame and feed. Simple.
It literally only took me an hour to tame a level 145 with only 50 mejoberries.
1. Gather berries and put the berries in your last slot
2. Kneel down and walk up to one of them and feed it the berries
3. Now you just follow it around while kneeling down and feeding it berries whenever it's hungry
4. Congratulations you tamed one.
Since they're commonly found in the red wood forest, I recommend only taming one if you're close to water as if you get attacked by something you can jump into the water to get away. Then when you think it's safe just go find your monkey and go back to following/feeding it.