I did Jay Gordon's method while we were still co-sleeping (I think she was 11.5 months). I'd been doing the pull-off thing for a while, so DD was sort of used to not being allowed to completely fall asleep on the boob. She was, however, feeding hourly (and had been since 8 months). I was exhausted, so it had to stop.
Night 1: Awake and crying a lot for 90 mins. I lay on my tummy (so no access to boobs), stroked her and told her to go to sleep. Her sippy cup water got thrown across the room a lot. Then slept until 6.
Night 2: Awake twice for an hour each time, less crying, but still very cross. Water flung across room. Then slept until 6.
Night 3: Awake for 20 mins. Drank water. Slept until 6.
Night 4: Slept through.
She then slept through reliably (even forgoing her 10 p.m. feed) until we moved her into her own room at 12.5 mo. That was pretty awful for another month, and I did feed her sometimes in the night. But then I got tough, moved my mattress out of her room, and if she woke I would only kiss her and then say night-night. No more boob. It worked.
She has her sippy cup of water refilled at 10ish when we go to bed (she drinks quite a bit as she's falling asleep), and if she wakes (rare) I just recite one of her story books to her in a droning voice until she falls asleep again. DH would rather I just left her to cry, but I don't feel comfortable doing that.
She did up her milk consumption dramatically during the day after I nightweaned. She went from six feeds to ten or something. But I didn't mind. I was happy she was sleeping! She's now down to one feed at naptime and one before bed, and even those seem to be waning (I'm 16 weeks pregnant, so I think my milk is drying up).
It's really easy to say once it's over that this or that method will work. But when you're in the middle of it, and DC is crying and you're knackered, you have no way of knowing when, or even if, it will ever end. But I promise it will, eventually.