when I tried to do this for gold a while back I was told that you can no longer be forced onto upgrade lists. You have to call at 72 or 48 hours respectively and ask for it. In my case I was dialing the number at 72hrs and 15 seconds
In all honesty I think its a good thing people cant be forced onto the lists anymore due to peoples ability to abuse it for friends
Just to follow up on this:
I qualified for MVP on my outbound SEA-EWR flight last Friday, 25 Sep 2009, though the miles still haven't posted. I tried calling this morning to request to be added to the upgrade list for my next flight (< 36 hours away now). The agent was very polite but swift in cutting off my request at the knees. She was adamant that the miles must be posted before she would entertain any upgrade requests.
I'm a little miffed, but not sure what else to try. The flight still shows as F7 U7 so maybe I can convince someone at the gate...