gistfile1.cs

protected void Application_Start(Object sender, EventArgs e)
{
    DataFactory.Instance.PublishedPage += Publishing_Page;
}

private void Publishing_Page(object sender, PageEventArgs e)
{
    PageData pageData = DataFactory.Instance.GetPage(e.PageLink);
    pageData.ACL.Add(new AccessControlEntry("MyGroup", AccessLevel.FullAccess, SecurityEntityType.Role));
    pageData.ACL.Save(SecuritySaveType.Replace);
}