There is no real ongoing program, if the airline needs additional captains, they will request names of individuals that are interested in their upgrade program.
You are basically resigning your current position to enter the program, so if you fail, you are now in no mans land, you will have to pay to get back to your previous position.
It is based on merit, if you are not in good standing with management, you will not get the opportunity. I think the last group of A320 guys that did the program had to put up a bond, plus agree to $15k for the training. As soon as you begin the IOE, you were in the past at full captain's salary, until that point you were not getting paid, you then have a three year obligation after completing the program.
This is just a rough idea of how it worked in the past, I also believe the contract agencies helped out with the bond in some cases.
Pilots that were accepted had already been around a year or two, hope this helps.
D.L.
