Download it and in ur sd card, create a folder named "media." Inside media, create two folders, one named "notifications" the other, "ringtones" copy the downloaded mms to notifications folder. Now u should see the mms in ur choice of notification ringtone. In same way, if u add a sound file to "ringtones" folder, the soundtrack will show up in ur choice for ringtones.
P.s. The folder names have to be exactly as I told you and all in lower case.