First, IMO I would get rid of the roo.
The actual "retraining" exercises are; Carry the rooster around for about half an hour like a football. Talk to him, stroke him, ignore him. Doesn't matter.
Second, kick him (like a football again) when he comes at you. Don't go overboard. I know someone that killed the rooster the first time.
Third, separate him from the flock. I believe two weeks was the time out suggested.
If you like having a rooster, there are tons of nice ones that need a home.