Magento: How to enable/disable module output per website level?

I would like to display an image in the onepage checkout payment methods section that would only show up in one of two website levels. So I have three questions:

1) Am I correct to assume this change would be coded in app/design/frontend/default/mytheme/layout/checkout.xml ?

2) if that is the correct file, what would the change be f开发者_开发问答rom:

<!--
One page checkout payment methods block
-->
    <checkout_onepage_paymentmethod>
        <remove name="left"/>

        <block type="checkout/onepage_payment_methods" name="root" output="toHtml" template="checkout/onepage/payment/methods.phtml">
            <action method="setMethodFormTemplate"><method>purchaseorder</method><template>payment/form/purchaseorder.phtml</template></action>
        </block>
    </checkout_onepage_paymentmethod>

in order to point to, for example, checkout/onepage/payment/methods-site2.phtml when site2 is being used?

3) Is this the proper way to do this in 1.5.x ?

1. Yes
2. You need add STORE_[your_store_code] handle and put there this store specific stuff. More info you can read in this article. So, in your case, you need update block with name root. To change block template you need some method for this, let's say its name is setTemplate. So, in your layout update file you should write

<STORE_your_code>
    <reference name="root">
        <action method="setTemplate"><template>checkout/onepage/payment/methods-site2.phtml</template></action>
        <block type="my_cool/block" name="my_cool_block">
        ...
        </block>
    </reference>
</STORE_your_code>

3. Yes, adding store specific handle to your theme layout update file is the right way for magento CE 1.5.x.