Getting involved with the event seemed a natural choice for the 1.90m tall, 109kg Chiefs captain.
"I sort of boxed when I was little, when I was a kid. One of my mates from intermediate school got me into it and just loved the sport from then. I still do quite a bit [of boxing training] for rugby it's a good way to stay fit. I've always wanted to have a fight," Messam said.
"This opportunity came and it's for a great cause - for prostate cancer. One of my mates fought threw prostate cancer ... Everything just seemed to fall into place, so I put my hand up and said yes to it."
The event is to be held on December 3 at the Trusts Stadium Arena, Auckland. It will feature six rugby stars versus six league stars, in an extreme battle-of-the-codes. The fights will be three two minute rounds of boxing and the money raised will go towards the Prostate Cancer Foundation of New Zealand.
Messam's team include Christian Cullen, Troy Flavell, Slade McFarland and Carlos Spencer. Jonah Lomu was an original team member but because of his recent health scare is unlikely to take part in the event.
Although Messam hasn't been matched with his opponent yet, the league team consists of Monty Betham, Awen Guttenbeil, Issac Luke, Wendell Sailor, Jerry Seuseu and Joe Vagana. Organisers are expected to match the boxers next week.