Check out the shipping pages.
I'm gonna ship my bike from Frankfurt to Toronto and return from Vancouver to Frankfurt. It's expensive but I think it's worth it. My flight cost is around $3100 for the round-trip and I can guess that if you fly it from London to Newark with Motorcycle express and back from say LA it'll cost you around $2500.
The biggest issue for you will be the insurance since the one I've seen doesn't allow you to drive offroad or even have it on a offroad oriented bike...
Hope all parts fall in place and you do get the trip done.