I'm no expert on FAA certification but, looking at Part 61 of FARs, you will need to get, at least, a FAA Commercial and IR before you can get a FAA instructor certificate. I'm sure someone will chip in with more detailed requirements (or go to the FAA website and read for yourself FAR61.181 - 61.199)
Given your training to date, none of these qualifications should present the slightest problem, apart from the time and money of course.
You will then have to obtain a visa which will allow you to work in the US - not so easy.
I suggest you talk, in the first instance, to flight schools that hold JAA approvals. Once you gain FAA certification, you will be more attractive to them than are FAA instructors who have no JAA qualification.