I think successfully training a rooster to subordinate themselves to people begins before the first act of aggression. My wheaten marans flock are just coming of age. I think the roosters of this marans variety are are spectacular.
Last month I was out collecting my eggs with my multi purpose egg collecting tool - a plastic landscape rake with a kidnapped wife's soup ladle duct taped to the one end. As I was working in the run near the coop the dominant rooster of the five perched himself on the ramp leading to the coop opening. Other than a chicken being beside me I didn't immediately take notice it was the alpha rooster eyeing me up at nearly my head level. Once I realized it wasn't a hen I turned my tool around, became a left hand hitter and put the plastic take up against his posterior and lifted him into 'fowl' territory in the run. Other than his pride being hurt and ruffled feathers, he struted away from me just as grandly as ever.
Now a little more than a month later, he still gives me a wide respectable berth when I'm in the run. He'll piss around with the other roosters, he hasn't lost his standing but when I come in the run, he's as far away from me as he can get. He's probably gonna be a real bugger to catch when I move him to the breeding pen this month.
Success for me came by not letting him as a cocketel successfully display any aggression directed to me. I think once they do, its impossible to retrain them.