This is near the top of the career forum information page:

NOTE TO ATTENDEES RESERVING TO MEET WITH ALASKA AIRLINES: 2/3/16 - Owing to the high interest in "meet-and-greets" with Alaska Airlines, space is NOW limited in FRIDAY's guaranteed appointments to STAND-BY basis. Registered attendees may need to be flexible in schedule as meet-and greet priority for registered attendees will be extended in to SAT as well. If time allows you may be seen on FRIDAY if you are on site. Arriving on Saturday? Attendees may reserve for texting notification and registration will include admission to the event. Please stop at the Information Booth for your registration credentials/badge. There will be no registration onsite.

I don't know exactly what that means. What I'd like to know is where it was ever publicized that such a system was being used. I would have registered a whole lot earlier.