Svetoslav Todorov, Mark Kelly, Darren Anderton, Linvoy Primus and Vince Hilaire have all agreed to appear in the match at Fratton Park, which kicks off at 7.45pm.
It is also anticipated that IBV manager Hermann Hreidarsson and goalkeeper David James, both former Pompey favourites themselves, will switch sides for the last 20 minutes of the game as fans welcome the new era at the club.
Trust spokesman Colin Farmery said: "We are delighted these former Pompey legends have chosen to support what we are trying to do. We are sure their appearance will be a draw for fans.
"Since the news broke last week that PST were going to take on the club we have seen a spike in ticket sales, but we would urge fans to buy their ticket online or from the ticket office before the match to avoid queues on the night."
Pompey boss Guy Whittingham has pledged to field a strong line-up for the game which is also part of the Icelandic Premier League club's pre-season preparations.