// exemplo: onkeypress="return handleEnter(this, event)" ;

function handleEnter (field, event) {
   var keyCode = event.keyCode ? event.keyCode : event.which ? event.which : event.charCode;
  if (keyCode == 13) {
    var i;
  for (i = 0; i < field.form.elements.length; i++)
     if (field == field.form.elements[i])
       break;
       i = (i + 1) % field.form.elements.length;
       field.form.elements[i].focus();
       return false;
    }
   else
return true;
}