This can be done by using a storeExpression action, put this action in the beginning of your Selenium Script:

  <tr>
    <td>storeExpression</td>
    <td>javascript{var date = new Date();date.getDate() + 
          '-' + (date.getMonth()+1) + '-' + date.getFullYear();}
    </td>
    <td>currentDate</td>
  </tr>

Now you can use the currentDate variable somewhere else in you script:

  <tr>
    <td>type</td>
    <td>startDate</td>
    <td>${currentDate}</td>
  </tr>