havick is right, I just did this. Came to USA with NO FAA certificates, just a verified Australian licence.
Completed all training (within the company) with no FAA licence (not even an FAA PPL) then the type rating check at the very end is also the ATP flight test. The only written exam I had to do was the FAA ATP-MEL. I now have an FAA ATP-MEL with a CL65 type rating.
Not at Mesa so not sure how they approach this but why would anyone go there ?