My DD also has cerebral palsy and she has been on all the rides except Space Mountain, Rock N Roller Coaster and BTMRR. She needs to be lifted out of her wheelchair and put on all the rides. My best advice is to save MK for a day when they are feeling really energetic. Almost all the rides at MK require a transfer and since most of them are short, just as you are getting settled, it's time to get out.
You can follow the link in my signature to get to the disABILITIES Board.
Here's a
link to the DIS page about touring with mobility disabilities. It has a list of rides that are Mainstream Access (which means wheelchair users wait in the same line with everyone else). There are some rides where wheelchair users board at the exit - this gives extra time, space and more control of the boarding process for CMs. In most cases, you will wait in the Mainstream line and just before you get to the boarding area, there is a bypass to the wheelchair accessible entrance.
On
this page from the official Disney site, you can download copies of the Guidebooks for Guests with Disabilities that DramaTech mentioned. They do give some general info about boarding. In general, boarding takes very little exta time, although for some rides, you will be waiting at the boarding area for a while because they can only have a certain number of people with special needs on the ride at a time for fire/evacuation reasons. Some shows have a limited number of wheelchair spaces and if they are all filled when you get there, you will have to wait for the next show even if there is still room left for general seating.
Kilimanjari Safari has a separate boarding area for guests with dsiabiliteis who have wheelchairs or
ecvs. The trams (even most of the ones that board at the regular boarding area) can hold up to 2 guests remaining in their wheelchairs. The wheelchair boarding area has a ramp for putting the wheelchairs on the tram and the tram returns to the same area for unloading so guest who left their wheelchairs or ecvs at the boarding area can get them. The regular tram boards at one place and unloads at another.