Build a trap, if you have an argentvis just build a trap without a ramp cuz argys can carry these guys when you finally got them with an argy just drop them in the trap you built and start knocking it out with a tranq arrow or dart,you can feed it with raw meat or prime meat or kibble if you want it to tame faster, just kill titanoboas (they have prime meat) with your argy since they live on the same area as kapros