By letter of intent do you mean a letter that expresses your continued interest in the school? If so, then it's hard to know how a gesture like that is going to be interpreted, but I think hand delivery is going to make you look desperate. Imagine how you would feel if someone that wanted something from you just showed up somewhere they knew you would be. It's not a good look. Just put it in the mail or send an e-mail.
If it's a letter detailing your intent to attend a school that has accepted you, then hand delivery is fine and the format isn't really important as long as it says that you accept their offer and are planning on attending their school.