Agree with many of the others - my son is a sophomore and I asked him today and he said he'd never heard of any shuttle services or the possibility of any way to get to Denver from the academy other than getting a ride with friends or the academy arranged buses (or a sponsor). However, I did a quick search and found the following, which I'm guessing is one you're looking at since it drops/picks up right at the Academy Hotel:
http://www.coloradoshuttle.com/prices-n-schedules.php
Interesting because I didn't know after 2 years this was a possibility! I would agree though that you'd need to get a taxi from there - I know for big events (Orientation back when they had it, I Day, etc.) there are shuttles, but I think they're provided by the academy and that's just one stop point. I'm sure the hotel can help him with a taxi though.