I am inclined to agree with Mme Frog......At least I'd advise anyone who was thinking of doing an IMC with a view to getting an FAA IR to use an IRI to cover their arse. But still, only 15 hrs is required with an instructor anyway which in terms of money equates to about $500 in the USA........You could do it in the sim in 3 days.......
I don't know which is 100% right, but as the FAA have this "CFII" rating - Intrument Instructor, authorised to teach for an ICAO IR it'd be reasonable to assume that you need to have previous training done my an instructor authorised to teach for an ICAO IR......
Just my view of course, though if you ask the FAA it probably won't make it any clearerer
