The Quebec government's tourism office works with an organization called Kéroul (a play on the words, on wheels). Their website is at http://www.keroul.qc.ca/en/
I checked the information about the falls. They are considered partially accessible. They do provide visual and hearing impaired services.
You can contact Kéroul via their website or by calling +1 (514) 252-3104 and the government tourism deparment is at +1 (877) BONJOUR
They may also be able to provide you with information on transportation. We call it Transport Adaptée (Adapted transportation) in French. While they may speak English, using a term like Transport Adaptée should help. It's pronounced Transpour Adaptay.
Good luck. And if you need more help, drop a line on here.