Boys last played for the Highlanders last season and came on as a substitute in the win over the Crusaders in Nelson.
He has joined the squad for the rest of the year after season-ending injuries to John Hardie (toe) and Doug Tietjens (knee).
James Haskell, the other option at openside flanker, has to sit out the next two games because of suspension.
Boys (28) is an experienced flanker and has played 35 games for the Highlanders, many of them off the bench.
Hale T-Pole is still with the squad and, along with Boys, is an option to play on Saturday against the Hurricanes.
The Highlanders still have the option to bring other players into the loose forwards but no-one else has been considered at this stage.
No 8 Elliot Dixon was also knocked out for the season, after tearing a pectoral muscle in the game against the Sharks at the weekend.
The Highlanders arrived in Auckland last night, on the long haul back from South Africa, and will train in the City of Sails today, before flying to Dunedin this afternoon.
Midfield back Shaun Treeby has travelled with the team.
There were fears Treeby would have to stay in South Africa after fracturing his cheekbone in the match, but he was cleared to travel, although his playing season is over.
