You first have to join the ACF. You then have to be a CEC (certified executive Chef) for 5 years (I think). Then you have to personally know (or have worked for) 2 master chefs, who would feel so compelled about the job you did, that they would recommend (and subsequently write a letter to the panel, recommending you as a candidate to take the test).
Once this letter is accepted, it's usually 2 years preparing for the test (which is 5 days long), and total costs are approximately 15K USD (including travel, food, lodging...etc), and that's just to be able to take the test....there's no guarantee you'll pass.
Oh....and by the way......currently, there are only 64 master chefs in the United States, with a very large percentage of them who were executive chefs in the Atlantic City casinos. These guys are not only masters of food, but masters of running some of the largest resorts in the world (let alone the US)
Look up Chef Heiko Bendixon, he heads the judges panel to certify master chefs, but he was the Executive Chef at Caesars palace in AC, about a year before I started there. Staff would still bring his name up from time to time, as what an incredible chef he was. He was/is the KING of multi-outlet, multi-tasking, in a city that saw over 250 million visitors a year, for 30 years.