Tree Tops Crazy Rider based on the Central Coast of NSW offers fun for everyone as shown in the video below. It shows how people with disability can participate. The main website provides the general details including costs and opening times. Scroll down their page for information on accessibility.
The ride is accessible inasmuch as it can be in a natural environment. Due to being situated in a State forest the pathways are gravel and the toilets are portaloos (there is an wheelchair accessible one). Professional team members provide expert assistance with equipment and safety requirements. You can see more detail in the original post.
Also check out Camp Manyung in Victoria for their inclusive activities and a great video showing a tree top course designed for everyone.