"Jack [Shephard] is on the short list of folks I would follow into Mordor"
Well, I’m not sure you would have made it "into Mordor". My guess is between his frantic yelling on the fringes of the Emin Muil (bringing every orc in the district down on him) and his cocky, dismissive ways with Sam and Gollum, the half-life of the Fellowship of the Ring would have been about 20 minutes.
"He also said that he would follow Jack Bauer not only into Mordor but straight up to Sauron, because Jack would probably torture him."
Jack Bauer would have killed Sauron with his thighs.
Then he would have melted the ring by staring at it.