yes, you can enter residency training under a special sorta 'training' visa, cant remember exactly what it is, but you would have to come back to the UK after your years in residency-its not for permanent moval to the US. If you are a fully qualified consultant in teh UK, i think it would be somewhat easier, especially if they want you.
If you want to do your residency training you would have to enter the 'match' after taking your USMLE exams (have a look on Wikipedia for this-looks like hell)