I've never heard of "slot pull" but If I had to guess, it may be like a slot tournament.
A slot tournament is when you sign up, they give you special machines to play on, it's always max bet and unlimited amount of credit, however you only have a limited time, maybe a minute or so to try and win (score) as much as possible.
Only the top scores will end up on the board and depending on the type of tournament it is, they could have any amount of winners, with one grand prize maybe.
I hope that helps.
Carnival-Paradise Sept, 2007
Carnival-Pride Aug 31, 2008
Carnival-Splendor Sept 6, 2009