The IR exams are included in the 14 ATPL (H) exams.
2 tips for people doing the FAA IR then converting to EASA - make sure you do at least 60 hours of seriously accurate flying (not the usual VFR slopping around) and make sure you cover the ADF/NDB, which is not necessarily used in the US. Otherwise your training will be "as required".
As mentioned, any IR is better than none, and you may want to look at getting a twin rating while you are over there and it is cheap.
Phil