.

:: app/design/frontend/base/default/template/opc/onepage/billing.phtml

INCLUSÃO DA INSTRUÇÃO DISPLAY:NONE NA TAG <li>

:: Na tag <li> inclua o respectivo bloco de código ...

:: style="display:none"

<!-- Cerebrum_Telencephalon -->

 <li class="fields">

 <div class="field">

     <label for="company"><?php echo $this->__('Street Address') ?></label>

     <div class="input-box">

         <input type="text" name="billing:rua" id="billing:rua" value="" title="<?php echo $this->__('Street Address') ?>" class="input-text required-entry" />

     </div>

 </div>

 <div class="field">

     <label for="telephone" class="required"><em>*</em><?php echo $this->__('Number') ?></label>

     <div class="input-box">

         <input type="text" name="billing:numero" id="billing:numero" value="" title="<?php echo $this->__('Number') ?>" class="input-text required-entry" />

     </div>

 </div>

 </li>

 <script type="text/javascript">

 //<![CDATA[

 setInterval(function() { 

 item_id = 'billing:street1'; // Informe o ID do campo do endereço nativo do Magento

 document.getElementById(item_id).value = document.getElementById('billing:rua').value + ', ' + document.getElementById('billing:numero').value;

 }, 1000);

 //]]>

 </script>

 <!-- Cerebrum_Telencephalon -->