Unfortunately there is not much you can say when they are actively drinking. They don't have the ability to love anyone when they don't love themselves, and they can't see the effect it has on others.
My RABF did the same thing with rehab. Said he wanted to go, was ready. I picked up the phone, made the arrangements, then handed the phone to him. I packed for him, got his documents ready. The next morning I wake up and he's in the family room...drunk. Said he changed his mind. I was heart broken, but I just said okay. And I let him know I was done, he was on his own figuring this out.
A week later, he comes to me and says he's ready. I gave him the phone number of the place that accepted him the prior week, but I didn't make the call this time. I didn't pack for him. I didn't ask any questions. He did ask me for a ride the next morning, and I did drive him there.
I learned "Mean what you say....and don't say it mean" during my own recovery. So don't make threats if you're not ready to carry them out. Keep going to AlAnon, it took me awhile before it all came together.