This is how to add a Breadcrumb entry in an own block:

$breadcrumbs = $this->getLayout()->getBlock('breadcrumbs');
$breadcrumbs->addCrumb('home', array('label'=>Mage::helper('cms')->__('Home'), 'title'=>Mage::helper('cms')->__('Go to Home Page'), 'link'=>Mage::getBaseUrl()));
$breadcrumbs->addCrumb('cms_page', array('label'=>$page->getTitle(), 'title'=>$page->getTitle()));