You might as well go for it all and ask how you can paint like Leonardo DaVinci, sculpt like Michaelangelo or hoop like Michael Jordan. If everyone could play chess like Bobby Fischer or golf like Tiger Woods, play hockey like Wayne Gretzky or run like Usain Bolt the world would be a pretty dull place. Those guys are special because they cannot equaled, they were the best that ever did what it was they did, and they can be imitated but never equaled.
In short, you can't box like Roy Jones Jr., nobody could he was one of a kind.
You can try but almost certainly will fail, boxers like Roy Jones Jr. are not only rare but one of a kind and the speed and talent he had can not be trained because it was God given.
Roy Jones did not box correct. He had some major flaws. He was such a good athlete with exceptional speed and reaction time he could get away with it.
The only roy is roy...be yourself.
Look at his style and copy it. Other than that you can't.