As a warning to any All Whites supporter who is going to Mexico City for the first playoff game - I recall a game between Mexico and South Korea I attended in Los Angeles. It was a mass of boisterous Mexican supporters, a small knot of Koreans and neutrals like me. When South Korea scored drinks and debris rained down on the Korean supporters from the sea of Mexicans surrounding them. Then to my astonishment one Korean (probably an ex-marine as they all seem to be) got out of his seat, climbed over several startled Mexican supporters and thumped the Mexican who had thrown something at him. Then he climbed back over the row of Mexicans and sat down. I wouldn't recommend it but it was the most reckless and bravest thing I've ever seen.
If you're going to the game, take your hard-hat.
A Mexico game in LA is tame compared to Mexico itself. Likely there will be fencing and federales there for your safety.
Here's a clip from the end of a nil-nil draw between the US and Mexico there
http://youtu.be/BJ5SlTdR5hQ?t=8m
This is one of the reasons CONCACAF teams hate Mexico and are pulling for the All Whites to eliminate them!