I will echo what shartito has already said. You can forget about all Opioids while you are being maintained on your Naltrexone (Vivitrol). They won't do anything and you would be better off investing your money elsewhere. As far as Alcohol is concerned, Naltrexone is considered a fairly effective treatment for Alcohol abuse, as for many, it tends to reduce the euphoric and positive effects of Alcohol. The only way you will find out if this applies to you is by experimenting.
Personally, I would accept your situation. You're dealing with the law and are obviously embroiled in some shit if they were able to force the shot on you. I would take this opportunity to take advantage of the effects of the shot. Why not just forego the Alcohol and try to better yourself? I'm not judging you at all. I would say the same thing to myself if I were in your position. The fact is, you've been given the shot, there's no "choice" in this matter until the shot wears off.