Some questions. Is he an intelligent boy? Is he intelligent, but dislikes school? Does he really want to go to college, or does he feel he has to?
Good questions by allmymarbles.
I would also add that the thing that might help you and him the most is to understand what ADD is and does to a person who has it. There have been posts on this site by kids in college who are making it without meds. But it takes a lot of work. You really have to work on study skills, etc. Once you know you have ADD, it does explain the problems in studying and the procrastination. The trick is to put that information to your advantage.
Some references to check out.
I usually recommend the book, "The ADD/ ADHD Answer book," by Susan Ashley. Usually more for parents of kids just getting diagnosed. But its still a very comprehensive quick, all encompassing book.
Another interesting book is by a UC Berkley honors student with severe ADHD. While it is about growing up with ADHD, not ADD you do get a feeling for what he had to do to get by in school. The book is called - "ADHD and Me, What I learned from lighting fires at the dinner table," by Blake Taylor.
Finally, a web site. Its really for adults. Your son is very close to that. Its about how adults (and college students) deal with ADD. It has many topics on dealing with ADD. You might want to check it out first. Its - http://jeffsaddmind.com/for-first-time-visitors
Hope some of this helps.