Javascript for perptually recurring donation. See the link for suggestions about CSS for the added disclaimer.

perpetual_recurring.js

<script type="text/javascript">
  $(document).ready(function () {
    var term = $('select[name=TERM]');
    var disclosure = 'Your recurring donation will be automatically deducted '
      + 'from your account on a monthly basis.';
    term.parent()
      .after('<input type="hidden" name="PAYPERIOD" value="MONT"/>')
      .after('<input type="hidden" name="TERM" value="9999"/>')
      .after('<div class="perpetual-disclaimer">' + disclosure + '</div>')
      .remove();
    $('select[name=PAYPERIOD]').parent().remove();
    $('#recurring_options').html($('#recurring_options').html().replace('times', ''));
    $('.link-help').hide()
    $('#recurring').click()
    // If you would like to have the donation page be only for the monthly amount
    // and not have an option for a one-time amount, then remove '//' from the next line.
    //$('input[name=recurring]').parent().hide()
  });
</script>