Dineen was selected by the New York Islanders in the second round, 42nd overall, in the 1981 NHL Entry Draft. Following his junior career, the Islanders assigned Dineen to the Indianapolis Checkers of the Central Hockey League (CHL) for the 1982–83 season. In 73 games with the Checkers, Dineen scored 10 goals and 57 points. Dineen was named the CHL's Most Improved Defenseman and Most Outstanding Defenseman. In 13 playoff games, Dineen had two goals and 12 points, helping the Checkers win the Adams Cup. Dineen also saw limited action with the New York Islanders, playing in two games in the 1982–83 season and did not score any points.