Vivitrol is the extended release form of the drug. Since the Sinclair Method is sensitive to timing, I imagine that the usual Hydrochloride form is preferable, which goes by the brand names Revia or Depade. However, it's already generic, so no need to pay for brand names!

It's prescription only, but it's not scheduled. The ease of obtaining it is likely dependent on how willing your doctor is to bend rules, or how well you can convince him or her that you are suffering from alcoholism. Even the experimental doctors want something plausible to write down however. They may be more persuaded by the mention of other applications of the drug, such as the trials on gambling addiction.