also, keep in mind that ESPN's TV broadcast is the primary focus of the events. Their live broadcast reaches millions all over the world. Even if you are backed by one of the top sponsors (last year it was Ford, Red Bull, US Army, and Mobil 1), those sponsors are given full access to the ESPN photo pool, and therefore, their photographers are given crappy access. The whole purpose is to keep everyone out of the TV shot and logistically out of mind as much as possible for the on site organizers. Expect some of the worst shooting conditions you've ever shot in for an organized event, and expect none of the ESPN organizers to be available to assist you with access.
I'm just trying to prepare you ahead of time.