First of all, good luck. I come from a long line of suckers, and we were successful at weaning one of my kids and unsuccessful with the other, so you might have to try a few things...
With my son, simply taking the pacifier away cold turkey before his second birthday did the trick. He asked for it a few times and we feigned ignorance, and then he was over it. The process took less than 24 hours.
My daughter, now 3 and both a thumb sucker and a paci addict, used only pacifiers until we tried weaning her. Shortly before her second birthday, we tried the cold turkey method that had worked so well for her brother and she outsmarted us by just beginning to suck her thumb. We immediately gave the pacifier back. Now, one year later, she takes either paci or thumb - whatever is on hand. We're basically back to square one.