Steve Lott says that Cus told Rooney just before he died: "all the works been done, just keep him busy". Lott says that Cus spent five years working closely with Mike at developing technique more than anything before backing off and watching over Rooney with him in 1985. So Cus learned him the D'Amato style to a tee by 1984, and ordered Rooney to just keep him busy just before he died (after a year looking over Rooney to make sure they were a secure team and on the right path).
Here's how Lott describes how Mike trained in his prime:
"Mike would run early, perhaps 4 AM or 5 AM. Then head to the gym at noon. This would be the same routine whether the fight was in Las Vegas or Atlantic City. Kevin would modify the amount of sparring depending on the days remaining before the event. If I remember correctly the most he ever sparred in any session was 10 rounds. The one thing that Kevin and Mike did in training that I rarely see is the ferocity of the sparring. Each round of sparring was expected to be a real fight.
And the sparring partners were superb. Among them were Jesse Ferguson, Oliver McCall, and Mike Williams. We taped much of the sparring for review later on in the day and looking at this sparring now many of these rounds were better than 95% of the heavyweight championship fights in the past 15 years.
At night Mike would relax or sometimes head to the health club to ride a stationary bike for an hour or so."
Kevin Rooney quote on sparring:
"About two or three days before the fight I would have him do 15 or 16 rounds with two or three different sparring partners just so that he knew he could definately go the full 12 rounds. I'm old-school, I believe in hard work."
Kevin Rooney quote on shadowboxing:
"Cus had a problem when fighters only approached shadowboxing as a warming-up exercise, which was literally all of 'em! What they do is - they simply go through the motions, f*** around doing f*** all, stab at the air, before moving onto the so-called real workout on the bags. But once you are in the ring, you will be confronted by different opponents who will use different styles and techniques. If you've already seen this guy, played these situations out and predicted your reactions as you shadowboxed, that puts you one step and one punch ahead of your opponent. Think in terms of combination punching - it's how big, heavy guys like Floyd Patterson and Mike Tyson got their hands moving quick as f*** and their combinations flowing like f*** - without the resistance of a bag or the impact of hitting an opponent to affect your punches, it's shadowboxing that is the time to concentrate on the importance of throwing more than one shot at a time. Taking this approach will create a good habit of punching in combinations. It will also help you to become more fluid in your delivery and create better balance between your footwork and hand activity. Do not throw a meaningless punch, without an opponent to fend off or a bag to react to, you have the time and clear thinking to concentrate on the punches you throw. Throwing a lazy jab or a slapping right hand out doesn't help you in the ring, so do not do it in training."
Kevin Rooney on weight-training:
"Mike never touched weights when he was with me, he didn't need them. If he was on the weights then he'd of been much slower than he was, you don't have faster hands than Muhammad Ali when your on the weights."
Kevin Rooney quote on heavybag:
"Mike's punching power was developed through hitting heavier bags over time, we had him on a 350lb bag just before hewas about to turn pro in the fall of 84' but he injured his hand after a few weeks so we didn't use that again."
Kevin Rooney quote on food:
"He lived off steak and chicken, it was damn expensive to keep him fed. Mike's favourite food was Captain Crunch and I used to let him eat it by the box load to fill him up."