The former 250GP winner will be replacing regular Team Suzuki GB rider, Tom Bridewell, who broke his leg at the opening Italian Superbike championship round at Mugello three weeks ago.
Mc
Williams's last competitive outing was on the Ilmor at the opening MotoGP round in Qatar last year, although he did not race due to injury.
The Ulsterman has been undertaking testing and development duties in recent months, as well as providing tuition with the Racedays Superbike Academy. He has never raced at the historic Monza circuit.
McWilliams has spent some time in recent months mentoring his fellow Ulsterman, Grant Molloy, who is partnering Bridewell in Team Suzuki GB this season. The 21-year-old picked up three championship points in the opening round at Valencia last month.
"I'm having a ride to try and impart some circuit knowledge to Grant and the two Racedays Superstock 600 riders, Danny Brill and David Paton," said McWilliams as he prepared for this weekend's racing. "Monza is a truly historic track but I've never raced here. I might have to get Fabrizio Priovano to show me round!"
McWilliams and Molloy will be joined in Team Suzuki GB by another wild-card rider at Monza - Australian Brendan Clarke who has the distinction of being the youngest ever points scorer in 500cc/
MotoGP.
This weekend's GSX-R Cup action kicks off with 45-minutes of qualifying practice at 17.10 local time on Friday, followed by a further 40 minutes on Saturday at 18.20.
Sunday's eight-lap (46.344km) encounter is scheduled to start at 14.20, immediately after the World Supersport championship race.
