Messam, capped 45 times for New Zealand in the 15-man game, joins fellow All Black Sonny Bill Williams in Gordon Tietjens' 14-man training squad for the Las Vegas and Vancouver legs of the sevens World Series.
The squad to play in the United States on March 4-6 will be trimmed down to 12 next week, and Tietjens said Messam was would not be considered for game-time until Vancouver the following week.
"I think spending another week with us in Vegas with a plan to playing him in Vancouver will be really good for him," the coach told local media.
Messam tweeted: "A lot of rust to get out of the system but grateful to be back with the @nz7s brothers."
New Zealand will be favourites to win gold when sevens makes its Olympic debut at Rio.
(Reporting by Ian Ransom; Editing by Nick Mulvenney)
