Like Esh, I took quit smoking after a few MC's, though not on my first. Believe it or not, I smoked off an on throughout my first few MC's. I *definitely* don't recommend that, and in fact I think it is VERY harmful. During my third or fourth cleanse, I didn't have any cigs until day 9, when I smoked two, and then I felt HORRIBLY ill the next day, and I *know* it was from those two cigarettes. That was enough proof for me that cigarettes are concentrated poison and I have not had one cigarette since then, it's been at least six months. In fact, I don't even consider a cigarette, I just think about how sick I felt after those two and that's it.
RE: drinking - I stopped drinking in Sept 2002, about a year before my first MC, so I had already dropped that addiction. If you are really an alcoholic, you might need something like AA to help.