$template->{level1}->{level2}->{element1} = '1234';

##</code><code>##

$template = {
              'level1' => {
                            'level2' => {
                                          'element1' => '1234'
                                        }
                          }
            };

##</code><code>##

$template = {
              'level1' => 
                         [ 
                           {
                            'level2' => 
                                        [
                                          {
                                            'element1' => '1234'
                                          }
                                        ]
                           }
                         ]
            };