i graduated 05. it was 2% of the graduating class could apply for consideration. USMA has its own board to select which candidates are then cleared to apply directly to medical schools.
an even bigger obstacle is finding time to study for the MCAT (or premed subjects in general) while at the academy. want to major in something other than premed but still want to go medicine? forget it. my class was also the first year that had the "chemistry life science" major. before then it was straight chem or chem engineering. (no bio department). also, research opportunities are virtually impossible (no time!). nowadays everyone pretty much has to have some research experience when applying for med school.
during the process, my classmates and i were HIGHLY encouraged to apply to USUHS in addition to whatever civilian schools (HPSP) we were applying. HPSP has an additional commitment of 4 years on top of the Academy 5. (more if you do a residency > 4 years). oh, and none of the active duty service obligation begins until after residency is over.
if serving and being in the army is important to this high school student, it'd be possible to do it this way. painful but possible. if this person is more interested in medicine than the military, than it's probably advisable NOT to go to the academy. many of my classmates at WP were exceptionally bright and talented but buried in all the BS that goes on at the academy.
does make you build pretty thick skin, though.
to be fair, WP is a different environment. have experiences you will never get anywhere else. learn and grow as a person and all that. and apparently civilians are impressed by it. some of my interviewers were more interested in what the academy is like as opposed to why i wanted to go into medicine. (one interview was entirely about rumsfield and how i thought he was culpable for a lot of the problems we were/are in at the time).
can PM me for more details/q's.
bottom line: not the easiest or best way but high level of motivation and an open mind can still make it work.