I canNOT speak for USAFA but there is no such opportunity from USNA and I would suspect not for USAFA. Once you're on active duty in the USN, there is a way to get the Navy to pay to send you to law school. However, it's not easy and you incur an add'l 6 yrs of commitment (in addition to the 5 from the academy).
In my view, if your desire is to be a JAG, you should pursue an alternate commissioning source. There are, I believe, programs for each service (assuming you've already graduated college) whereby the military will send you to law school. You should check with an officer recruiter for details.