ok, i found a solution:
1 - i created a new department for the french language
2 - i generated a new code for this department to include in the page i want the hcl module appears
3 - i created a french.    php file (translate the english.    php file in french)
4 - i installed it in the hcl/lang directory
5 - finally i edited the hcl/ config.    php file and replace the line 79 ($conf['lang'] = 'english'; ) by the following code:
   
if (isset($_GET['departmentid']) ) {  // the departmentid is generated when you create a new department  
       if ($_GET['departmentid'] == 2){   // id of my 2nd department
      $conf['lang'] = 'french';
      }else{
      $conf['lang'] = 'english';
      }
     }
        else{         // for the admin side (if you omit it, you will have an error in your admin page)
      $conf['lang'] = 'english';         
   }