Hi, I'd like to help you with your question.
It sounds like you have done a lot to try and help your brother. Having a family member who uses alcohol can be very difficult, painful and frustrating all at the same time. You are doing everything you can think of to help, but they are not responding.
It sounds like your brother has tried treatment, but he is not following through and staying sober. One of the most important points to clarify is whether or not your brother is motivated to become sober or is he only motivated by others to become sober? If he is motivated himself, that is a very good sign. He will be willing to seek out help and at least try to follow through and stay sober. If he is motivated by others, however, then sobriety is extremely hard to obtain and continue. The motivation must be with him and him alone.
If he is motivated and wants help, then he needs to seek it himself. He can call a treatment center and talk with them about treatment options. If he cannot pay, he can talk with them about payment options. He needs to contact them himself. The motivation to become sober must be there for him. He is the only one that can stop his drinking.
As painful as it may be, you and the rest of his family need to let him seek his own help. Making him do it when he is not motivated only keeps him from being responsible. It also damages your family and cause pain. If he always has his family to take care of him, he will not learn to care for himself. There also will not be any motivation to change since he does not suffer consequences to his alcohol use. I understand that you are fearful of him driving while using and that is fine. He should not be allowed to drive. But it may be time for the police to become involved since he needs to understand his use of alcohol is dangerous and can harm others. It would also help him seek treatment since any judge that deals with him will most likely order treatment. This can only be a good thing for him.
When you do have contact with him, refuse to stay if he is drinking. Do not pretend that his alcohol use is not dangerous. Be open about the effects of his use and do not hide your pain or the consequences of his behavior on you and other family members when he drinks. The more you tip toe around him, the more he is protected from the consequences of his alcohol use. And that lessens the chance he will get help.
Consider joining Al Non to help your brother. They are there for families of alcohol users and they can help you find ways to help your brother. You can find them at http://www.al-anon.alateen.org/.
There are also some books that may help you. One is called How Al-Anon Works for Families & Friends of Alcoholics by Al-Anon Family Groups. Another is Sober Siblings: How to Help Your Alcoholic Brother or Sister-and Not Lose Yourself by Patricia Olsen and M.D. Petros Levounis M.D.. You can find these on Amazon.com or your local library may have them available.
I hope this has helped you,