Hi,
This is what worked for me....I dropped one feeding each week. Try the easier ones first. At nap time I would have a sippy cup available but I didn't push it since I didn't want to replace nursing with something else. For the most part this process was pretty smooth, but I was always ready to distract if needed...bike ride, park, walk, car ride, play dates. Keeping him busy really helped. Once I had dropped all but the morning feeding, I then dropped my pumping (I was only doing once a day, if you're doing it more than once a day drop one per week). Pour whatever pumped milk you have into the bottle and fill the rest w/ soy or cow milk. My Ped. suggested switching to a sippy cup and dropping the bottle once my son turned 1. I haven't accomplished this yet, but I have been reducing his bottle by 1/2 ounce per day, once you get to 3 ounces start replacing milk with water, 1/2 ounce at a time until it is all water.
My only strong advice is to start this when you can really commit. I've had friends see saw back and forth i.e. "they really wanted to nurse todday so I gave in". That makes it so much harder for you, baby and your milk supply. The other thing is don't add bottles to replace nursing, you'll just have to break those soon too.
As for pain, I haven't had any at all. Since this process has taken a month, my body has had time to adjust and it has been pretty easy. Right now I'm still nursing in the morning, I have a sippy cup full of soy milk in clear view for him. Since my supply is so low each morning my son is reducing the time nursing by a minute or so. I think he may just loose interst on his own. GOOD LUCK!