R.,
consistency with putting him back in his bed, even at the expense of loosing sleep. Assure him that you love him and send him on his way. If you do not do this each and everytime he will keep returning. It is a learned response now, like Pavlov's Dogs salivating at the bell.
My son who is now 5 went through that I would sometimes let him stay just so I could sleep... wrong move. Instead of a few days it took almost 3 months before I saw a consistent pattern where he'd remain in his bed. I am also a teacher so know the morning feeling with the kids!
Bottom Line: Simply tell him to go back to his bed, or walk him back, no words neccesary other than tucking him in with a kiss an I love you, and good night. Consistent and firm just like Super Nanny will eventually work, but get some cream for those dark circles under the eyes...SMILE
S. A.