We are in the middle of this process - our baby girl is 2 months old. I read the Healthy Sleep Habits book. It gave good advice about the sleep window but it is definitely pro-CIO and I had some other problems with it, I won't go into... I don't think CIO destroys people for life but I'm not crazy about it as a mama & want to try other solutions. I liked the book Sleeping Through the Night better.
At first, she hated being on her back anywhere. She would only sleep in her swing or with me on my boob (and would startle awake if I moved at all - so you can see why we need to phase out co-sleeping - so that I can be rested and sane after going back to work). However, I cannot let a baby this young cry without intervening for anymore than 5 minutes (or less if the cries are escalating).
So here's the drill: I breastfeed her, check her diaper, and swaddle her before putting her down. We started putting her down for naps, and then moved on to putting her down for the night. The key is to watch for the sleep window, whenever that happens (the schedule apparently comes FROM their natural rhythms) - don't miss the window - we look for the yawn, the tired lidded eyes blinking slowly - then rock a little with her over the shoulder while singing, then rock a little holding on her back - while eyes are still open but sleepy. That's all the routine part. Then into her crib, in this elaborate setup: first years cosleeper that we had had in our bed (that she hated sleeping in the whole first 2 months, even though we were right there), sleep positioners at her sides, used nursing pads in the corners so she can smell her mama, putting her either on her back or alternating sides, then turn on the homedics sound machine on rain. Make sure both cats are out of the room, close door.
The REM cycle is 45 minutes. Sometimes she wakes at 45 minutes and cries very halfheartedly for less than 2 minutes and goes back to sleep - that much CIO I can live with. If she wakes anytime after 2 hours, I go to her and check the diaper, then bring her to nurse in side-lying position and sleep with me the rest of the night. The key is to do a routine and start in the crib, get through a few REM cycles with some self-soothing, and over time that first block in the crib will get longer and longer until it's morning. That's the theory, don't know if it will work... so far we have been getting longer and longer blocks but her stomach is still so small that I think the maximum for now is 4 hours. Still, 4 hours of sound sleep for me, followed by 4 hours of less-sound sleep is better than 8 hours of less-sound sleep was. Hope this combination of techniques is helpful. At first I thought there was no middle ground between CIO (where the baby's emotional needs for security are not met) and attachment parenting (where the parents' physical needs for sound blocks of sleep at night are not met), but now I'm starting to think there may be a middle ground possible. Good luck.