What is best way to get slotted for ALC since I am coming up with 1 year TIS and getting ready to go to Korea for 9 months?

Go straight to the root , you branch manager, you are about to go to Korea, so you could ask for TDY in route, that is your best bet, your unit won't want to pay for your school because your are leaving and Korea won't send you because is only a 1 year tour, so your best chance is now on your way to Korea or on your way back from Korea

Best bet......pester the living hell out of your unit Training NCO with ATRRS request forms until you get a reservation confirmation. If that don't work, pester the living hell out of your BN Ops NCO with ATRRS requests until you have reservation confirmation.

I would suggest going directly with branch. CW3 (Join to see) has a good point. What caught me off guard when I attended in 2012 was the Common Core requirement (a distance learning course). I don't know if this is still applicable, but it was required for graduation credit (even after completing phase 1 and 2). We had to get help getting slotted for that course from the school house directly.