+1

I recently completed the 14 ATPL exams. Definitely high school level material, but there is a lot of quantity. There were a few FAA ATP holders in my class and two Americans.

Probably the easiest and least costly way to get the JAA ATPL would be to do the 14 ATPL exams via distance learning, (if you hold an ICAO ATPL such as the FAA ATP, you can self certify for the exams and not need to enroll in a course, so you could buy second hand books from Oxford or Bristol and study on your own plus get a membership to one of the question banks).

Then, if you have a type rating on your ATP with at least 500 hours on type, you can take a flight test in the simulator with a JAA examiner observing, and you get the type rating on your JAA license. Plus you need to get an Initial Class 1 through a JAA AMS, not just any JAA AME.

JAA ATPL is a waste of money if you aren't using it. Also, you get the JAA ATPL and you go 7 years without keeping it current, you lose your exam passes.