Jewell said: "Bill is coming to assist me directly, and will be looking after the tasks I don't have time to do now we are in the Premiership.
"I want to spend as much time on the training pitch as possible and not get bogged down in tiresome and time consuming paper work.
"He is part of my backroom team and will answer to me, as well as working closely with our chief executive Brenda Spencer.
"Brenda and myself have been a great partnership in getting things done, and Bill's role will be to ease the pressure on both of us."
Green, 55, said: "This is a really exciting opportunity for me to join Wigan Athletic at what is undoubtedly the most exciting time in their history.
"When you look at the progress Wigan has made both on and off the pitch in the past four seasons it's been incredible and I can't wait to play my part in continuing that.
"The role is wide ranging in responsibilities, but essentially I'm working for Paul Jewell and I'm here to assist him in any way he asks.
"I'll be spending a lot of my time meeting with players and agents, as well as doing other general football admin and even some scouting in Europe."