Shannon has played one ODI and one Twenty20 international for Ireland, making his debuts in May and November 2013.
"James is an extremely talented batsman who is rated very highly by myself and the selectors," Ireland coach Phil Simmons said. "He was part of our trophy-winning ICC World Twenty20 squad in the UAE, and was unlucky to miss out in the original selection. Hopefully he'll take this opportunity to showcase his undoubted talent."
Shannon will arrive in Trinidad on February 6 and Ireland play their last group game in the Nagico Super50 against Windward Islands the next day.