Both played key roles in Wednesday's famous 1-0 victory over champions Manchester City.
O'Neill said: "They can be a threat and this is the whole point. If we can get the ball out to Adam sometimes a wee bit more quickly than we do, then he can cause problems.
"You would hope that would be the case. With James, we sat here a couple of months ago and we were talking about this second season syndrome, and I was hoping that it genuinely wouldn't be an insurmountable problem for him.
"I knew he would have difficulty early on, and that was shown by the number of times that full-backs went to close him so very quickly in matches.
"He is learning to cope with that know and I am hoping he will overcome it. But still, he will have games where he will be unable to do anything, simply because players have either marked him or things didn't happen for him.
"But overall, he is coming through."