The 36-year-old Republic of Ireland international has been without a club since leaving Elland Road in the summer, but will imminently join the Championship strugglers.
Freedman told reporters: "Paddy Kenny is a very experienced player. We have had a difficult time last week with Adam Bogdan's freakish injury so Paddy is going to come in on a short-term contract.
"He is looking forward to getting back into training day-in, day-out and he will be looking forward to playing some games, no doubt, knowing Paddy.
"I think Andy Lonergan has done ever so well and he has got the jersey to keep and Paddy is there to back him up and hopefully to make sure training is done right and the attitude is right between the goalkeepers."
Kenny has also previously played for Sheffield United, Queens Park Rangers and Bury.