I don't disagree with the experiences and advice that have been posted in this thread, but my own experience has been very different. I take wine enemas frequently in large quantity. When I first started I would take about 1/6 of a bottle of wine at a time (a refilled Fleet enema bottle) and increased the amounts gradually. Now I take a full bottle of up to 12% wine in a single enema. This is the same amount of alcohol found in five beers or five shots of 80-proof liquor. Five drinks in a row is the definition of "binge drinking."
It gets me drunk, but not so fucked up that I can't function. Bear in mind that I'm a big man, 6'5" and 280lbs, so my resistance is higher than that of most people. It does get me drunk faster but I couldn't say that I get more drunk with an enema than with regular drinking. I'm also far less likely to suffer a hangover the next day, although that could be because I usually take my wine as a part of a day of enema play, so I remain pretty well hydrated.
I remain aware of the dangers of alcohol enemas and I accept them, just as I accept the dangers in seeking out poz, unmedicated men for barebacking.
I do not recommend beer for enemas for several reasons. The yeast in beer can cause an intestinal yeast infection, since it has not been broken down by the stomach's digestive enzymes. The carbonation in beer can cause severe, uncomfortable bloating and flatulence.
I found this interesting testimonial regarding alcohol enemas: http://bearslairforum.com/enema/WineEnemas.html I don't endorse any of the claims it makes but my own experiences have been very similar. In particular I agree with the writer's recommendation that you start with very small amounts (too small, ideally, to even notice the effects) and to increase until you find your comfort level. Be aware that everyone's metabolism is different and you could have a serious reaction to an amount that I wouldn't even notice. For my own part, I'm planning to cut back to no more than two bottles of wine per month because of the effect it's been having on my blood sugar, from a controlled low of 125 up to, more recently, readings in the low 200s.