Hi P.,
I had a similar situation with my son. I swear if I hadn't done something he'd still be nursing to this *day*!
I had talked with a La Leche League leader and his pediatrician and they both pretty much said the same thing, let him wean at his own pace. We'd been nursing only at bedtime and upon waking for over a year. At two and a half years and able to have fairly involved conversations, I was really ready to be done. Eventually I talked with my doctor. It happened to be right before Thanksgiving... a nice long weekend. She suggested I stop nursing Wednesday night and that he would be fine by Monday.
Wednesday night at bedtime I told him there was no more "nurch" for him and, "doctor said nurch all gone." He was pretty upset for about 15 minutes, maybe even a little angry. I dreaded the morning, but when he got up he said, "Nurch all gone?" I confirmed and that was the end of it. I was quite relieved at how easily it went.
I know there's room for a lot of fear-mongering available on just about any topic, including this one, so just remember not to let fear be your guide. Toddlers truly aren't damaged by stopping nursing, but from withholding love and affection. I'm sure that will not be how you do this.