How do I get Montezuma to surrender to Cortez?

Hint 1 of 5:

You'll have change the myth of Quetzlcoatl in the past.

Hint 2 of 5:

It would help if you could talk to a priest.

Hint 3 of 5:

The only priest who will help is in 44 BC.

Hint 4 of 5:

Do what you have to in order to change the myth.