Tonge, who graduated from the famed Sheffield United academy and played for the Blades in the Premier League before moving on to Stoke City, enjoyed his first day of Barnsley training after his loan switch from the Potteries.
Hill swooped for midfielder Tonge and Norwich City midfielder Korey Smith earlier this week, but still wants to strengthen his squad.
“We’re still wanting to add two permanent additions to the squad before next Tuesday,” said Hill.
“We see Michael Tonge as a player who can unlock doors.
“He’s not played a lot of games but he’s got the quality in abundance that we’re always searching for.
“Tony Pulis (Stoke manager) has done us a great financial deal.
“Korey, also, is an essential addition to the squad.”