The South African international has been training with the Tractor Boys during pre-season and played in their 2-1 friendly victory over Crawley Town.
"I was pleased with Bongani," McCarthy told The Green Un. "He's very quick and athletic. I thought he did okay. I'm pleased with him.
"We're not looking to buy or sign him, we're looking at a possible loan deal."
Khumalo arrived at White Hart Lane from Supersport United in January 2011, but has been loaned out to Preston North End, Reading and PAOK.