To get miles on American for your flights, fly one of the following: American, TAM (Brazil), Aerolineas Argentinas, Grupo TACA, or LanChile. If you're looking for status miles, AA and LanChile are the ones you need.

LatinPass is a frequent flyer program covering (I think) nine airlines in the Central America/northern South America region. Its partners outside the area are US Airways, KLM, and National Airlines.