I don't think you can do anything special. I know we received 2 dreams on our last trip...we were named "Family of the Day" at Pop Century and received VIP admitance to the Nemo musical. For the PC thing I just got a knock on the door one afternoon and there was a CM standing there with a picture frame and a certificate. We did absolutley nothing....although they had MAJORLY screwed up our reservation and we had a huge fiasco getting rooms at 1A the night before so we always joked that that was Disneys way of making it up to us. There were a couple of times that we were stopped by Dream Squad members and my MIL would make a HUGE deal over how this was DSs first trip...he got his very first haircut there, etc. and that seemed to kinda turn them off. They would just congratulate us and smile and move on to someone else. When we got Nemo VIP seating I was just checking the scheduled board and a CM asked if we wanted to see Nemo that day. I told her that was what I was looking at the times for and she pulled out a VIP seating card for us.
So my advice is to not expect anything...just go in to enjoy Disney and maybe you will get lucky!
