i have tried to patch the file by using the tutorial of Lord Banshee. See thread: "SoftfireGl works with RT 15.3 for 8.062 drivers!!!! But not sure at 100%" I was not able to patch the first file with the SoftfireGL script. So i think you have to take the 62 one.
not working for me. the latest driver it works is 8.062. maybe a new rivatuner will be able to do it.