The 31-year old striker is enjoying a successful spell on loan from QPR and after scoring eight goals in 12 Championship outings, McCarthy is keen for him to stay at Portman Road past January.
"They will have all noticed DJ scoring goals here but there is nothing we can do about that," McCarthy told the club's official website.
"All we can do is try and do a deal with him. He wants to stay long term at a club and I think this club would be his first choice, with things starting to go better.
"But there are a lot of mitigating circumstances that can change that situation. Let's just wait and see."