Can I attach a javascript function to a Drupal.behaviors javascript function?

I want to trigger another function any time Drupal.behaviors.MultiPage (found in field_group/multipage) changes page.

It’s part of this code:

Drupal.behaviors.MultiPage = { 
  attach: function (context) {
    $('.multipage-panes', context).once('multipage', function () {

      var focusID = $(':hidden.multipage-active-control', this).val();
      var paneWithFocus;

      // Check if there are some wrappers that can be converted to multipages.
      var $panes = $('> div.field-group-multipage', this);
      var $form = $panes.parents('form');
      if ($panes.length == 0) {
        return;
      }   

      // Create the next/previous controls.
      var $controls;

      // Transform each div.multipage-pane into a multipage with controls.
      $panes.each(function () {

        $controls = $('<div class="multipage-controls-list clearfix"></div>');
        $(this).append($controls);

        // Check if the submit button needs to move to the latest pane.
        if (Drupal.settings.field_group.multipage_move_submit && $('.form-actions').length) {
          $('.form-actions', $form).remove().appendTo($($controls, $panes.last()));
        }   

        var multipageControl = new Drupal.multipageControl({
          title: $('> .multipage-pane-title', this).text(),
          wrapper: $(this),
          has_next: $(this).next().length,
          has_previous: $(this).prev().length
        }); 

        $controls.append(multipageControl.item);
        $(this)
          .addClass('multipage-pane')
          .data('multipageControl', multipageControl);

        if (this.id == focusID) {
          paneWithFocus = $(this);
        }   

      }); 

      if (paneWithFocus === undefined) {
        // If the current URL has a fragment and one of the tabs contains an
        // element that matches the URL fragment, activate that tab.
        var hash = window.location.hash.replace(/[=%;,/]/g, "");
        if (hash !== '#' && $(hash, this).length) {
          paneWithFocus = $(window.location.hash, this).closest('.multipage-pane');
        }   
        else {
          paneWithFocus = $('multipage-open', this).length ? $('multipage-open', this) : $('> .multipage-pane:first', this);
        } 
}
      if (paneWithFocus !== undefined) {
        paneWithFocus.data('multipageControl').focus();
      }
    });
  }
};

/**
 * The multipagePane object represents a single div as a page.
 *
 * @param settings
 *   An object with the following keys:
 *   - title: The name of the tab.
 *   - wrapper: The jQuery object of the <div> that is the tab pane.
 */
Drupal.multipageControl = function (settings) {
  var self = this;
  var controls = Drupal.theme('multipage', settings);
  $.extend(self, settings, controls);

  this.nextLink.click(function () {
    self.nextPage();
    return false;
  });

  this.previousLink.click(function () {
    self.previousPage();
    return false;
  });

What I want to do is track anytime the user clicks the “Next” or “Previous” buttons – the code that triggers this is at the bottom of the snippet.

Is there a way for me to bind an event handler to this function?