Service Academies recruit in the same manner as other schools. They are allowed quite a bit more latitude in the recruiting process than normal schools though. For instance, the coaches are not restricted to calling only seniors since the admissions process is so much longer.
Good luck, and if you have any specific questions, be sure to ask here. One poster, Academydad, has had a cadet playing baseball at Air Force and Navy, so he'd be a great resource for you.