In the book, Ferguson discussed Keane's controversial interview with the club's TV channel, in which he criticised O'Shea and Darren Fletcher among a number of then-United players.
"Roy was always wanting the best and he'd always look out for me," O'Shea told Irish radio station FM104. "He only wanted the players to improve all of the time. He's a winner and he wanted to be the best.
"Obviously books through the years can be a slight exaggeration or whatever. The people that are involved in the books have to sell the books, they highlight certain things. Books can be misleading in some senses.
"In my eyes, he was always very good to me, in terms of wanting me to do better and wanting me to improve. That was always the case with any young lads coming through and I'm sure Fletch would say the same as well."
Keane now works alongside Ireland manager Martin O'Neill.