Use the advanced search option to google the exact phrase
dialect coach and take it from there. You'll get thousands of search hits including anecdotes about gazillions of established actors and actresses preparing for a part with the aid of such a specialist. It's a profession by its own right; it wouldn't be if there were no need for it, or at least producers wouldn't pay for it, which they do. Needing a coach to pick up an accent says nothing about whether you're a good actor or not. After the age of twelve it's virtually impossible to analyze and acquire a "foreign" accent unless you're a phonology genius. Some people are, most people aren't � either way it's not related to your acting skills.
By no means should you make a particular point of finding an Irish-born coach. What you need is someone who is skilled in analyzing an accent/a dialect and making you hear what you didn't hear before. The mere fact that a person is a native speaker does not automatically provide him with those qualities. Hey they can even be American � but as
your speech should be the point of reference, they have to work with you live, books and tapes won't suffice if you
really want to "pass".
The
Kira Method ;-) of watching how people's mouths move may sound a bit daft but it's very good advice. Ask a professional impersonator, they'll tell you the same thing. 'Course, what happens "on the inside" (tongue, vocal folds, resonating chambers et cetera) is even more important � but imitating how someone "holds" their mouth will help you develop a feel for what's going on "inside" as well.
Now
there's a genius
Break a- �tongue?
spiraltree!