Ok well we had quite a few factors going on aswell, I think it helped to tackle it really slowly and bit by bit and not even think of when it would all finally fall into place.
It was dh that did it really and it's not really cc, I don't know what it is but it's a pretty wimpy method. He started off going in and sitting in the rocking chair singing away to him (this song that he has always sung to him and soothes ds instantly). Always staying til he went back to sleep. Then after a few days when ds figured out he wasn't going to be picked up dh changed to not singing but just sitting in the chair. Then VERY VERY gradually staying less and less time. Eventually he would just go to the door and touch his head lightly or say 'ssh' and ds would go straight back to sleep. This was when dh completely stopped going into the room at all and ds would cry out and then go straight back to sleep. After a night or two he didn't even cry out.
But the key is that it was a really gradual thing. Try to look at each stage as it's own acheivement and not get too fixed on wanting it all to be fixed straight away iykwim. I know I was always really impatient and the thought that this could take weeks just wore me down. Traditional cc would not doubt be quicker but we couldn't go that route.
I tried a similar approach at bedtime when I had got myself into a bad situation of rocking him to sleep. Just going from being tied to sitting next to him til he fell asleep to staying less and less each time (regardless of if he fell asleep or not) until finally just putting him down, saying night night and leaving.
We never went back in because I know from my own experience that it would make him more hysterical. If he ever did cry more than 5-10 mins after I'd left we'd go to him and just do it again, sit a few mins til he calmed down, then leave. It sometimes took me 45mins. But there was only a couple of nights like that.
But I am far from one to advise. Ds has been sleeping through all of a week! Hope I haven't jinxed it now...
good luck, it is so hard.