<?xml version="1.0"?>
<config>
    <modules>
        <Mymodule_Page>
            <active>true</active>
            <codePool>local</codePool>
            <depends>
                <Mage_Page />
            </depends>
        </Mymodule_Page>
    </modules>
</config>

<?xml version="1.0"?>
<config>
    <modules>
        <Mymodule_Page>
            <version>1.0</version>
        </Mymodule_Page>
    </modules>
    <global>
        <blocks>
            <page>
                <rewrite>
                    <html_pager>Mymodule_Page_Block_Html_Pager</html_pager>
                </rewrite>
            </page>
        </blocks>
    </global>
</config>

<?php

class Mymodule_Page_Block_Html_Pager extends Mage_Page_Block_Html_Pager
{

    public function __construct()
    {
        echo 1;
        exit;
    }

}