On the Universal Forum, there was a ticket that offered a 2 park 1 day pass with roundtrip transportation from Disney resort. We used it on our last trip and it was great (check out my trip report). You call the night before and tell them the time you want to go and they pick you up right at the red carpet at POP (Near Luggage). When we called we expected a taxi van because there was 9 in our group but a huge bus came to pick us up with other Disney guest on it. It was nice. Our bus driver was the best!
I am sure you can call Mears the night before you go to set up a pick up time w/o the tickets that I bought.