Once you are approved you only need to email them the conf# of your flights to have your status added.
There is no "Waiting list" for free upgrades, nor will you find elite literature anywhere about free upgrades, as officially that is not an elite benefit.
What is official is the ability to practically guarentee yourself a paid upgrade by purchasing it the day beofre the flight.

Now, i have had 100% success on my past 20 flights or so, (all either to or from cak) on getting upgraded for free by check-in or at the gate, sometimes w/o asking, but most times by asking at the gate.

Basically as long as there is an empty seat you will be upgraded!