yeah......... umm i think you should have a room called "The Fastpass Station", and people could come and say what they want a fastpass for, and then you pm the person who is monitoring the ride the person wants a fastpass for (assuming a cast member monitors each room) to let them know that they will be getting a fastpass. i know it sounds kinda confusing, so here's an example:
you are monitoring the fastpass station.
guest1 walks in and wants a fastpass for the backlot tour.
you pm staff1 who is the cast member at the backlot tour and say: expect guest1 to be coming soon. they have a fastpass.
staff1 saves the message or writes down guest1's name on a piece of paper.
when guest1 arrives at the backlot tour, they approach staff1 and are admited to the fastpass line.