5 or 6 years ago I was working in Mexico on computer control systems for water treatrment plants. While there I met and worked with a young Mexican programmer who was fantastic. Since I was the head of my department when I got back to the states I immediately began working to hire him.
As I recall there is a list of approved jobs and skills that the U.S. has in order to be eligible for work here. He did not exactly match the list so we stretched the truth a little in order for him to qualify. I think it took us about 6 months to get the paperwork cleared. There is probably such a list available today as well.
I think he has to update his visa or green card once a year. As far as I know he is still working for the company. I have since left.
A brief search on google turned up the following link:
http://www.visanow.com/IMMIGRATION_V...er-shuffle.asp
You might want to look into what they call an H-1B visa. Good Luck.