<?xml version="1.0" encoding="UTF-8"?>
<config>
    <modules>
        <XYZ_Checkout>
            <version>0.0.1</version>
        </XYZ_Checkout>
    </modules>

    <frontend>
        <routers>
            <checkout>
                <args>
                    <XYZ_Checkout before="Mage_Checkout">XYZ_Checkout</XYZ_Checkout>
                </args>
            </checkout>
        </routers>
    </frontend>

    <global>
        <models>
            <checkout>
                <rewrite>
                    <cart>XYZ_Checkout_Model_Cart</cart>
                </rewrite>
            </checkout>
        </models>
    </global>
</config>