The one that I have would actually work quite well for that-- it has wheels that and handholds that allow you roll it when it is folded up and it is made to stand upright when folded. It is somewhat heavy so you would probably still want to be able to take it up the ramp on to the bus-- not sure how that would work with a lift though. You could carry it up the steps if you really needed to.
However it is a pretty expensive model. I was very lucky to get it as a resale at a very good price.
http://www.rascalscooters.com/index.cfm/mobility/products.detail/scooter/Fold-and-Go®-370/id/15
The other question though, would be if the Disney would allow this. Usually scooters are tied down for their protection and that of the people on the bus. A folded
scooter is much heavier than a folded stroller and in case of an accident could do a lot more damage.