Put the files into the Script Menu folder (e.g. %ProgramFiles%\Sony\Vegas Pro 13.0\Script Menu).
Restart Sony Vegas or press Tools>Scripting>Rescan... to update script list. You should have a new option at Tools>Scripting>Resample....
If you're using Magix Vegas, then you can go into the Project Properties and change the Resample mode without needing this script.