While not directly Alaska related, relevant for many here since we fly out of SEA all the time and Alaska/Hawaiian do have flights out of both A and S gates.
The new Checkpoint 1
opens at long last on Friday at 4am. This checkpoint is located on the baggage claim by the international arrivals hall.
Note that to start it will be general screening only, but apparently once TSA has worked out any kinks with the checkpoint they will expand to have PreCheck and CLEAR there as well.