There are two scripts on that page that deal with auto voicing users, so which one you want to use depends on what changes need to be made. One of the scripts deals with people who have fservs and respond to !list, the second mirrors who is voiced with a second channel.
Each one has a section which configures where you want the voices to happen. After this section is added, just save the .pl file (as .pl, not .pl_) inside of your XChat profile directory, and it will be loaded on startup. You can also load the script with XChat -> Load Plugin or Script, although scripts won't be remembered by loading that unless the file is already in the profile directory.