Just a note, it only works for me if the site-specific package is coded like this:

sub config_data {
  return {
    starting_page  => 'www.yahoo.com/foo/',
    some_regex     => qr/foo(.*?)bar/,
    html_tree_spec => [ '_tag', 'div', 'id', 'headlines' ],
  };
}
[download]

With curly brackets not parentheses. Did I, or did you, get something wrong?