Just wanted to say that it is possible 
We've moved from co-sleeping, constant bf, waking ever 45mins-2hrs and some screamy-ness (aka living hell) to last night in about 5 wks.
7.30pm to 5.36am i am so happy... But will he do it again?!? I don't care at least i know that it is possible.
We went cold turkey on bf-ing between bedtime and 6-ish am, no feeding to sleep and he was encouraged to sleep in cot. He did not get left to cry alone ( and there was lots of cross crying
), me and dh cuddled, walked, rocked, sang and patted and offered him water and fridge milk as much as was needed... Some nights were pretty sleepless but he got it - am so proud/relieved.
And just as background .... His sleep habits were affecting all of us... Waking dd and dh too, frequently. I worked since he was 10m and i just couldn't think straight or function properly on so little .... "something" needed to be done.