Hi and

to disABILITIES!
Most lines in the parks are mainstreamed, which means that he will be able to ride his
ECV all the way up to the boarding area or to special seating in theaters. If an attraction had load and unload at different locations his ECV will magically show up at unload after leaving it at load.
There are some attractions where for various reasons (usually stairs) an ECV cannot go all the way; in those instances there is an alternate entrance to which he will be directed. Note that normally special treatment will be given to the disabled person plus five additional members of the party.
Almost all of the attractions can be slowed or even stopped to allow extra time to board or alight.
However, Peter Pan and the Tomorrowland Transit Authority
cannot be stopped.
Also, if you click on where it says "disABILTIES" at the top of this page it will take you to the Index. One of the top items is the "disABILTIES FAQ" which will gives lots of useful information. You may find Posts #2 and #4 especially helpful. Note that we recommend rental of an ECV from an off-site vendor so it will be available to him at all times (some of the hotel corridors are
very long) and the off-site rentals are much better than Disney's.
Or, if you want an easier route, click on the link in my signature.