They do not use the normal entrrances to the parks. Each park has different "VIP" entrances that the guides are allowed to park at:
1) Hollywood Studios: Just 1, near Lightning Mcqueen racining academy (which is the absolute farthest away from Star Wars Land you can get)
2) Animal Kingdom: 2, one in Pandora, one near Dinosaur. This is by far the best locations for VIP entrances.
3) Epcot: 2, one near Test Track, one near Soarin'. Note that the one near Test Track, I believe you can also exit into the Mexico Pavillion instead, since they are so close backstage.
4) Magic Kingdom: 1, near Buzz Lightyear.