Sorry, but not much of chance of hiring directly into OSA. There are two reasons: #1 C-12 slots are few and coveted, #2 Commanders need you to be a deployable asset (C-12 does deploy but rotary deploys much more, in the Guard). Yes, you will fly rotary at flight school, and have an advanced airframe (Chinook, Hawk, Apache), but I wouldn't want to pull you from fixed wing to bring you down range in an aircraft you have very little experience in(although it defintely does happen). Main reason, though, is really the seniority thing.
If you are interested in reserve component fixed wing, many Army Reserve fixed wing units are short pilots to staff deployments. I don't think they are hiring straight off the street yet, because you wouldn't be a deployment asset for 2 years or so. But it's probably coming due to post-deployment retirements.