Talk to Army Space S-1. I forgot their number, but call DSN 692-8750 or COMM 719-554-8750 and talk to the 24 hour site and tell them you want to talk to the person in charge of 1C assignments. It should be a female SSG and ask her if you can go TDY for the 1C course and in getting Okinawa.
Since you probably don't have enough time in service, you'll have to reenlist. I'm sure in that case, they'll give you a requisition number for you reenlistment. Good luck.
A 25S in 1/1? I didn't think they had any. I'm down here in okinawa with 58th sig. There's a satcom unit with us that probably has some 25s slots to fill. But hey, I'd want to be in 1/1 too, they flip tires and what not. Who wouldn't want the what not.
Oki's a good place to be, but you might find yourself twiddling your thumbs.