I went through this stuff myself about 6-7 years ago, but how do you get the "certified proof" mentioned below? An instructor is an instructor, unless he is a fake, but nobody is in a position to produce a "certified proof" of ability to do a particular lesson.
TRAINING BY NON-FAA INSTRUCTORS: Applicants wishing to credit instruction provided by non-FAA instructors must present to the examiner certified proof that the non-FAA instructor was indeed authorized to conduct such training OUTSIDE THE US ONLY.