Greg Smith is the St. Louis-based chairman of the Milwaukee region's seventh-largest law firm, Husch Blackwell LLP, which is also among the nation's 200 biggest firms. But his story could have turned out very differently. Alcoholism nearly derailed his life 30 years ago, a story Smith first shared during a Husch Blackwell corporate retreat in Dallas and again this week with legal news publication American Lawyer. He described how his heavy drinking began in college, continued into private practice,…