Let's go back to first principles. No one is going to build giant Llama catapults to fling them from the Andes to Meso-America. That would be entertaining, but not realistic. Before we get there, we need to do stuff.
What we have now is communication and contact between Meso-America and the Andes, proven for a fact. But it's limited and intermittent.
We have Llamas and Alpacas in the Andes, beasts of limited burden for carrying packs, not big enough for riding, not really suitable for fulling a plow, not really good for milk, good for meat, good for wool, don't handle environmental hardship. In terms of useful domesticates, with cattle and horses being a 10 and turkeys being a 1, I'd rate them as about a 5.5, maybe a 6.
Now, if the objective is to get a viable population of Llamas up into Meso-America in sufficient eventual numbers that they're doing useful things, there are some challenges, and some POD options.
How about a deep time POD where Llamas really diversify and become useful. Where the Andeans start breeding larger and robust, and particularly more environment tolerant breeds. This isn't deliberate artificial selection - most of the diversity of duck, dog, cat, cattle, horse, pig, chicken varieties aren't the result of careful breeding, but simply a lot of genetic diversity, and animals being moved or used in different environments. Shetland gets ponies, the Mongols get ponies, the Knights got big ass clydesdales, etc.
So maybe all we need is some small cultural social tweak which results in Llamas proliferating much more widely.
What does this matter? Well, it'll change Andean societies, and that may have knock ons all over, including contact with Meso-America. And you might get more robust or specific-environment tolerant Llamas that will transfer to Meso America.
Or how about a median-POD. Forget the Llamas. We need at least one robust seafaring culture to emerge and develop really good boats and navigation for distance. This is not out of the question. We have hard core coastal/sea cultures from the Salish in British Colombia and the Pacific Northwest all the way down to the Andean coasts. The earliest Andean cultures were highly dependent on sea protein and the fishery.
Better boats, better navigation, allows for more and better trade opportunities. And this allows for more trade volume.
The big question is what goods get traded, what the priorities are, etc.