Change the server setting in the configuration from testhost.somecompany.com to productionhost.somecompany.com.

XML file:

    <?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <appSettings>
        <add key="server" value="testhost.somecompany.com" />
    </appSettings>
</configuration>

Build fragment:

<xmlpoke
file="App.config"
xpath="/configuration/appSettings/add[@key = 'server']/@value"
value="productionhost.somecompany.com" />

Modify the noNamespaceSchemaLocation in an XML file.

XML file:

    <?xml version="1.0" encoding="utf-8" ?>
<Commands xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="Path Value">
</Commands>

Build fragment:

    <xmlpoke file="test.xml" xpath="/Commands/@xsi:noNamespaceSchemaLocation" value="d:\Commands.xsd">
    <namespaces>
        <namespace prefix="xsi" uri="http://www.w3.org/2001/XMLSchema-instance" />
    </namespaces>
</xmlpoke>

The location specified by the XPath expression must exist, it will not create the parent elements for you. However, provided you have a root element you could use a series of the tasks to build the XML file up if necessary.