He forgets the small detail that he has a PHD and by definition he is an expert in his field so arguing that there is no other americans who can do his job is much easier, or at least there won't be many candidates avaliable. He is also married/marrying an American too.
I know 2 other people who's living in the States from the UK. One works for a pharmachutical company, the other has a PHD in economics, applied on the off chance and now works in Chicago, University of Illinois doing research (and another PHD).
So basically what everyone else has said, you need to have a company who sponsor you or do a job no other American can do.
In short, marry a yank (but you are already married).
Get a job for a company with an American office. (you are self employed).
Get specialised in something...PHD?

Invest a lot of money into the country.