codesmith msbuild task -- overridable .csp properties

I would like to be able to specify a new value for a property element in the .csp file.

Something like this?

 <CodeSmith ProjectFiles="GenerateMetaData.csp;GenerateIndex.csp">
    <property name="OutputDirectory">C:\temp</property>
 </CodeSmith>



My particular need is slightly more complicated --- I want to be able to set the connectionstring value in my .csp value.

Otherwise I might have to use a XmlWrite Community task, which would be yucky since it saves the file.