M.,
I actually used to work at a daycare about 18 months ago before my daughter was born, now I stay home.
I was in the 2 year old class room and when they got moved up from the toddler room many of them had blankets and paci's that they were attached to and were allowed to have during the day in their old room.
The other teacher and I really didn't like it when the children would carry a blanket or have a paci in their mouth during the day, it was only allowed during nap time.
All we did is about 2-3 days after they moved up we simply put it in their cubbie and would do our best to distract them and simply just not let them have it any more.
The reason we let them have it for the first 2-3 days is because it was a new room with new teachers and mostly new kids with a new routine, everything was new and the only thing normal and constant was their paci or blanket.
After nap time when they work up we would grab the blanket real quick if they set it down to play with something and same with the paci and once they noticed it was gone, if they did they could cry but we would just say all done, you only get it at nap time.
The interesting thing was after some time they grew to learn and be used to the fact that they were not allowed to have it during the day and would voluntarily put them away after nap and in the morning when they got there. But with many of the kids the second they saw mom and dad the didn't run to them they ran to their box and wanted their item which mom or dad would let them have right away.
So, I think the only thing you can do is simply not let you son have a paci except at night time, it will take a while, probably longer with you since he knows he gets his way and how to manipulate you (not saying your easy, kids are just smart like that) Then once you want him to stop using it at night and naps it will be hard because he uses it to fall asleep but do the same thing, I think it has to be a cold turkey thing where you are VERY consistent, no giving in because it's easier or you just want him to be quiet because if you give in once it's pretty much over and will take forever to get him to realize you mean business.
The only reason I know that will work is because we did it with numerous children at the child care center where I worked.
B.