The hardest thing about alcoholism is nothing works until he wants help for himself. We all want our parents to stop drinking and have tried to help them a thousand times. But until they do it for themselves it doesn't work. You can let him know you love him, if he is anything like my Dad was he probably won't care. You can tell him you will be there for him WHEN he does get help.
Meanwhile taking care of yourself is job number one. There is a lot of helpful information in the stickies above to get yourself started. I know from personal experience it is very painful to have a parent chose drink over family. But taking care of yourself first is the best thing to do when feeling torn between running and staying. It's like in an airplane and the oxygen masks drop down, they tell you to put yours on first before you can help anyone else. Learning more about this and how to treat yourself will help your Dad in the long run.
Are you near a city with any AA or Adult Children of Alcoholics meetings?