Know for a fact that having passed the atpl's doesn't restrict you from joining this course, though you might not want to have too many hours along with it, i'm guessing ctc prefer you to be trained their way if at all possible on the wings scheme.
But there have been guys with a few hundred hours which have made it onto the course and by now have finished and are flying with the airlines, so no problems there. It all comes down to the selection i guess, and how you put yourself across.
WBV