I did it gradually. I was getting blisters so I started to night wean at 13 months. My daughter was waking up every 2 hrs and it started to drive me nuts. It was a long process and she was fully weaned by 16months.
You can set limits. Start low..like I won't feed him until 2am. Once they get used to not being fed at that time, you can start upping the time so that the next one would be I won't feed him until 3am..and so on. Eventually he will catch on. Be patient but it will happen.
I night weaned my son at 23 months. ALthough I was seriously tired of nursing 2-3 times a night, I didn't really intend to wean and was kind of sad to be honest that is was over so ubruptly:( What happened was that I went away for 3 nights with my best friend and he stayed with his dad. I pumped a bit while I was away and actually got quite a bit even though I was 8 weeks pregnant and suspected that I might be losing my supply. Anyway, I got back and I offered the breast and he sort of seemed like he had forgotten all about it, nursed a tiny bit and that was it! Done and has only asked once since when I was holding him in a cradling position. He started waking once a night and I would read him a book while he lay in his crib and now he sleeps 11 -12 hours straight a night! Not sure what I will do with the next one because as much as I loved our long nursing relationship, my son's inability to go to sleep or resettle in the middle of the night without nursing made me a basketcase on many occasions!