If you go to a maritime school there is the MarGrad program. It too is on the Coast Guard site. From what I understand if you graduate from the Merchant Marine Academy, or any of the state Maritime schools you are eligible to apply to CG for direct commission and do not have to complete the full 17 week OCS.
I did have an instructor at Cal Maritime tell me that those MarGrad commissions with the CG are competitive and you would be in competition with all from USMMA, Mass., Maine, Texas, and Cali. for a CG commission....not sure how true this is, but wanted to pass it along.