How can I ease my son off his pacifier?

My son Etai is 16 months old and he is addicted to his pacifier. If he sees it he aks for it and crys until you give it to him. His teachers at his pre-school say that if he see's it in his cubby he crys for it until he gets it. I want to slowly ease him off it and keep it for naptime and bedtime until he's 2 years old.Any suggestions?