<?php

class Vendor_Extension_Block_Html_Rel extends Mage_Core_Block_Template
{
    
    /**
     * Get current category
     * @return Mage_Catalog_Model_Category
     */
    protected function _getCategory() 
    {
        return Mage::registry("current_category");
    }
    
    /**
     * Get current product collection
     * @return Mage_Catalog_Model_Resource_Product_Collection | null
     */
    protected function _getProductCollection() 
    {
        /* @var $category Mage_Catalog_Model_Category */
        $category = $this->_getCategory();
        
        if (
            $category && 
            $category->getId()
        ) {
            /* @var $collection Mage_Catalog_Model_Resource_Product_Collection */
            $collection = $category->getProductCollection();
            $collection->addAttributeToFilter('status', 1)
                       ->addAttributeToFilter('visibility', array('in' => array(Mage_Catalog_Model_Product_Visibility::VISIBILITY_IN_CATALOG, Mage_Catalog_Model_Product_Visibility::VISIBILITY_BOTH)));
            
            return $collection;
        }
    }
    
    /**
     * Get pager
     * @return Mage_Page_Block_Html_Pager
     */
    public function getPager() 
    {
        /* @var $collection Mage_Catalog_Model_Resource_Product_Collection */
        $collection = $this->_getProductCollection();
        
        if (
            $collection && 
            $collection->getSize()
        ) {
            /* @var $pager Mage_Page_Block_Html_Pager */
            $pager = $this->getLayout()->createBlock('page/html_pager');
            $pager->setLimit($this->getLayout()->createBlock('catalog/product_list_toolbar')->getLimit())
                  ->setCollection($collection);
            
          return $pager;
        }
        
    }
}

  
<?php /* @see Vendor_Extension_Block_Html_Rel */ ?>
<?php /* @var $this Vendor_Extension_Block_Html_Rel */ ?>

<?php /* @var $pager Mage_Page_Block_Html_Pager */ ?>
<?php $pager = $this->getPager() ?>

<?php if ($pager): ?>

    <?php if (!$pager->isFirstPage()): ?>       
        <link rel="prev" href="<?php echo $pager->getPreviousPageUrl() ?>" />
    <?php endif; ?>

    <?php if (!$pager->isLastPage()): ?>
        <link rel="next" href="<?php echo $pager->getNextPageUrl() ?>" />
    <?php endif; ?>
    
<?php endif;

<?php echo $this->getLayout()->createBlock('extension/html_rel')->setTemplate('page/html/rel.phtml')->toHtml();?>