It is recommended that you order your tickets on line and indicate on line that you have a disability.
Should you require it you can rent a wheelchair from the Cloakroom near the Efteling entrance.
You will need to submit a Declaration in order to obtain a facility card.
The request states that you are not able to visit the attractions using the normal queues, and you can indicate whether you are able to visit the attraction alone or whether you need the help of a companion (and possibly an attraction employee)
A maximum of three helpers can make use of these same facilities.
There is a maximum limit of two helpers at the De Vliegende Hollander.
You can see videos on the way you can access the various rides if you are wheelchair bound.
You may also receive a discount and a special park map.
More information can be found here