Coming from Nintendo's own FAQ...

QUOTE:

I live in Latin America. Am I eligible?
Answer:

For our Nintendo 3DS owners in Latin America, Nintendo will make the Nintendo eShop available for you to download the available free content including, Nintendo 3DS Ambassador Program games (for those that qualify), Nintendo Video and Pokédex 3D. To be part of the Nintendo Ambassador Program, please perform the latest Nintendo 3DS system update before 11:59 pm Eastern time, August 11, 2011.

To do this select System Settings from the Nintendo 3DS main menu > select Other Settings > select System Update.
Thanks to Pellican for the heads up!