The general gist of the comments here are spot on. The US , especially the cities, are very tough to break into.
You will almost surely need work authorisation. Many companies ( and recruiters) simply wont even look at you if you require sponsorship. There are 2 exceptions to this:
1. You have contacts there who will fight to get you there ( i.e. direct hiring managers)
2. You are so specialised, your skills are so niche, that not many people have those skills.
As one of the reviewers said, by far, your best chance will be to get ACN to post you for a secondment in the US office. This too is difficult and time consuming. I think you can understand that a company like ACN has many many employees willing to do exactly the same thing as you.