Nope... My ISP manages the RDNS for it's netblock.... I asked if I could do it... They said yes but I chose to leave it with them anyway. Since they own the netblock their RDNS server is authoritative and will override anything you want to try to do unless they delegate the authority "downwards".

When mailservers etc are checked by other mailservers I'm not entirely sure that the RDNS is a true RDNS query... I think it's more a comparison of sending IP and resolution of that IP to a hostname. I could be wrong but there's a lot of mailservers out there that wouldn't work if the request was a true RDNS request.