My DS was fed to sleep til he was weaned at 23 months.
He mostly co sleeps, so its really pretty easy to get him to sleep. If I'm uncomfortable I just put him in his bed later after he's asleep.
I still occasionally rub his back, or let him have a hand on the boob for comfort, but other than that I highly recommend co sleeping Even if its just til they're asleep.
He started mostly sleeping through a while ago, but has only been sleeping all night every night the last few weeks. Again another reason for co sleeping. I would just attatch him & go back to sleep.