The links given by pps are great, they both sound very similar in approach and hopefully you'll feel a connection with those descriptions/methods/steps towards independent sleep.
I personally feel the reward chart idea is way too complicated and actually puts too much of the responsibility on the child. Really can a child this age work out how 'minimally he can nurse'?? I don't think so. They *do* understand a lot at this age but this is quite an abstract thought to try to 'nurse less' and to get a star reward for doing so. It's not just that it's complicated but also that you would be expecting him to think of a reward system in the middle of the night when all he wants is to get back to sleep and the only way he knows how to get to sleep is to nurse.
To me this is like asking a 2.5yo to try to eat less chocolate - they just can't and neither should they be expected to. It's the parents role to decide if chocolate is appropriate (and how much) and if it is considered inappropriate then it is the adults job to ensure the child is not given any...not have it available and then say "try not to eat it" or "try to eat less and you can have a star on your chart". I see this weaning at night similarly, it is your choice to wean the night feeds so you make it happen, with zero responsibility put on the child (but barrow loads of love, cuddles, sympathy and understanding that this is a very hard thing).
When you get tears, frustration and anger (which I do think you will get at some point) I suggest lots of understanding sounds, lots of "yes I hear you" and "ahum, aha, yes, I know, yes", I believe he is going to have a lot to say about this and my approach would be to *hear* him. He is entitled to his thoughts and opinions on this change which he doesn't want and likely to feel much better about the whole thing if he is heard and understood - basically validating his feelings. Imagine a girlfriend telling you about something that has really upset her, she doesn't expect you to fix it or offer solutions or tell her this is for her own good or will be better for everyone in the long run, she just wants to be able to get it off her chest and for someone to say "yeah, I'm not surprised you're upset". I remember reading about this a couple of years back and tried it one night with my DS, instead of trying to stop him crying by any means I decided to really listen to his complaints and make lots of those sounds as though I was really listening to him...and he actually stopped crying much faster!
Good luck!