I had the CM notate it in our reservation when I booked. At CSR, the only request I made was to be in the Cabanas if at all possible. I didn't request a certain Cabana, since it doesn't really matter to me which, I'd just really prefer to be in the Cabanas!
In the past, every request we've ever made room wise has been met! It's clearly no promise, but it's my experience that they'll do their best!
I do need to have the DVC member we rented points from for our 1st two nights at AKV Kidani put in a request for us. We booked standard since that was all they had open, but I'd like to request standard pool view if possible!