Using the OAuth form:

  use Flickr::API;
  use Flickr::API::Upload;
  my $api = Flickr::API->import_storable_config($config_file);
  my $response = Flickr::API->upload({
               'photo'       => 'path/to/photo,
                'async'       => 0,
                'title'       => 'My vacation picture',
                'description' => 'Here I am, riding a horse',
  });