Magento & Google Chckout Tracking

HTML & CSS
1

I am currently using Magento to power my shopping cart. I am in the process on intgrating an afilliate network with my site. To do this I have to pass some tracking info to Google Checkout. So far I have this code:

        <merchant-checkout-flow-support>  
            <parameterized-urls>
                  	<parameterized-url url="https://track.webgains.com/transaction.html?wgver=1.1&amp;wgprogramid=4449&amp;wgrs=1&amp;wgeventid=7041&amp;wgvouchercode={$this->getCouponCode()}">
                      		<parameters>
                          		<url-parameter name="wgorderreference" type="order-id"/>
                          		<url-parameter name="wgvalue" type="order-total"/>
                      		</parameters>
          		</parameterized-url>
          	</parameterized-urls> 
            <edit-cart-url><![CDATA[{$this->_getEditCartUrl()}]]></edit-cart-url>
            <continue-shopping-url><![CDATA[{$this->_getContinueShoppingUrl()}]]></continue-shopping-url>
            {$this->_getRequestBuyerPhoneNumberXml()}
            {$this->_getMerchantCalculationsXml()}
            {$this->_getShippingMethodsXml()}
            {$this->_getAllTaxTablesXml()}
            {$this->_getParameterizedUrlsXml()}
            {$this->_getPlatformIdXml()}
            {$this->_getAnalyticsDataXml()}
        </merchant-checkout-flow-support>

The only part I’m worried about is the wgvouchercode={$this->getCouponCode()}. Does anyone know if the syntax of this seems correct? If not, how do I insert the value of any discount codes used into that parameter.

Thanks!