I don't know if there's still an installer for version 9 floating around out there, but after some testing, it looks like you can republish the voicepack in v.10 format if you still have all the original sound files. Launch RTST and re-load the voicepack file to preview a few sounds and make sure it's working correctly. Then just click the publish button and use the new v.10 file which will load automatically when you launch RTST from then on.