I was blessed with a son who slept anywhere, anytime. He slept in a bassinet in my room for the first 3 months, and then we put him in his crib... I rocked him to sleep until he was a year old. I was STAUNCHLY against letting him cry it out at all, at any age. Right about 13 months he started resisting the rocking, but wouldn't just lie in his crib (he'd get up, cruise around in the crib, etc...) and if we left the room he'd cry.
After about 2 months of pure h3ll at bedtime, I decided to try CIO, since he was old enough to know that we were right in the other room, and that we weren't abandoning. He totally shocked us - he cried (exactly
) 5 minutes the first nite, 2 the second and 15 seconds the third!
Babies don't know how to manipulate w/ their cries until 5-6 months, and if you don't mind sleeping with him, you are NOT causing him any harm or starting any habits by doing so until that age. Does he sleep in the car? My best friend's son ONLY sleeps in the car, and in the car seat in his crib! Swings, bouncy seats, exersaucers, etc... are all ok for a baby to sleep in as well -- wherever they sleep, let them sleep!
If I were in your shoes, I'd co-sleep until 5-6 months, try the crib again and CIO if necessary. . . Good luck!!!