There really isn't an absolute way to approach this question since people have different motives for drinking to begin with. You'd probably have more of an impact by gathering people who are close to the person, and having them express themselves and how they feel about that person's addiction. That includes describing character changes that the person undergoes when intoxicated. Sigh, support group, yay...
In terms of actions, if the person dismisses everything by saying, "I don't remember any of it," you could respond with, "but we do..."
To be realistic though, there are people who will blatantly disregard any concern from others, and as sorry as I am to say it, those people will have to find out the hard way, i.e., alcohol poisoning, liver failure, etc.
The latter is the case with a friend of mine despite everyone's unrelenting efforts, but I guess not giving up is key.
I don't know if this'll help much...