Didn't really know where to put this.

If you get a type rating that is NON-JAA, afaik it is impossible to convert it (like if I were to get an FAA 737 rating, that would not be convertable to JAA).
Is there however a way to do this if you have x amount of hours on that type?

You should be able to put it on your JAA license after 500 hrs on type. Might have a restriction on it until you have done an OPC in an EU regged aircraft. Check with the authorities in the country you have your JAA license issued in. Provided you have a JAA license to begin with of course.

Thanks.
I don't have my JAA license yet, but I'm in the process of getting one (working on the JAA ATPL at the moment)