I highly recommend the book 'On Becoming Baby-wise.' (Read the reviews on amazon.com. It has worked for a ton of people......I swear the people who criticize it have never read it... ) I've had a lot of luck with that book, those velcro swaddle blankets (my baby wakes himself up with his hands) and a white-noise machine. (the sound of the ocean waves) First we used the Sleep Sheep, but you have to push the button every 23 or 45 minutes. Now we use one that plugs into the wall and plays constantly (or on a timer) because now we need it to sleep too! Bed, Bath, and Beyond has a great one for 20 bucks.
The hardest habit to break is the rocking to sleep... I was the same way.......... During the day I admit I let my baby sleep in his sling or on me........(rocking in a rocking chair) But- at night, Daddy swaddles him and he gets put right in the co-sleeper...... (That might help to have Daddy do it... )He actually is happy being awake for a few minutes and drifts off to sleep himself. This took some time... There were a few times I had to say- "I'll just give him a minute..." Each second feels like an eternity and it breaks your heart... But- then I'll look at the clock and realize it was 30 seconds to 2 minutes... etc... (waking up in the middle of the night)
My friend told me about their transition to the crib. She sat a chair next to the crib and slept in there for a few nights. The first night she was right next to the crib and would put her hand on her baby's belly to comfort him when he cried....... Each night she would move a little further away. I think she said it took about a week..... Now she'll hear him on the monitor cooing and playing by himself a few times during the night, but he doesn't cry. At first he would only sleep in his car-seat... they would literally put the car-seat into the crib! LOL!
Maybe you could replace the rocking with a different night-time 'ritual' that lets you put the baby down and drift off to sleep by herself. (usually on a timer) There's that Fisher Price soothe and glow sea horse that lights up and plays music for 15 minutes. Target has it for 15 bucks. Or- that Fisher Price Rainforest waterfall soother.
Good luck! Sorry for the private message... Most people hear about the book 'Babywise' and start spouting insults and lectures... M. :)