A while ago i wrote about a Clever TemplateFile hack to use some xml block as ReplacementValue. Today i realized there is a clean way to achieve this by defining the value as CDATA:
<TemplateTokens Include="mex"> <ReplacementValue> <![CDATA[<endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />]]> </ReplacementValue> </TemplateTokens>