The best thing to do is to ween SLOWLY! Most moms, myself included, can make such a big deal over trying to wean, that our child ends up nursing more than usual! Instead of offering a pacifier, which she knows you're using to replace something she wants, offer to walk around with her and sing to her, cuddle her, read to her. you may lose sleep for a couple of nights, but she doesn't feel like her comfort is being taken away from her. That's why she's waking up at night to nurse. Habit and comfort. It's a nice feeling at night. If you just try to stick something in her mouth and hope she goes back to sleep, chances are it will make her upset and want to nurse even more.
Try explaining to her, "we'll have nursey (or whatever you call it) when the sun comes out." Something to that affect. Point to the window and explain to her how it's dark outside and when she sees light, she can nurse. Use simple terms, and chances are she won't understand exactly what you are talking about, but soon she'll get the idea that, okay, when it's dark, no nursing, when light comes in the window, I can nurse!
It takes awhile, but it usually happens once you stop trying! I tried and tried, and I'd lose so much sleep listening to my son cry and cry and cry, and my sister finally said, "S., take it easy! The more you push it, the more he wants it!" And sure enough, as soon as I just distracted him calmy, without making any big deal of it, he stopped. I did the whole wait for the sun thing, and he'd still wake up, but he'd look out the window, go back to sleep, and as soon as he'd see that sun, he'd smile and go right for the breast!
The key is not to make her feel like she's losing something. Cuddle her, sing to her, and after about 10 minutes, go ahead and nurse. Go a few minutes longer each night until she gets the hint. Each time, though, explain the whole sun thing. She'll get the hint and feel much better about quitting on her own! Just don't stress her out and yourself out, also. You want this to be a peaceful transition.
I believe letting babies "cry it out" is actually harmful to them. At this age, they still need to be loved and taken care of and feel secure. If she's waking up and crying for a few minutes, that's one thing, but I would strongly recommend not letting her go for very long without some type of comforting. Even if it causing you to lose some sleep, research shows answering a young child's cries (not just baby, but young child) is beneficial to them mentally and emotionally. Babies who were allowed to stay in their cribs and cry were far FAR more likely to end up suffering from depression as teens and adults.