Add the following to the <system.net> element in the web.config to push webservice calls through fiddler.

  <defaultProxy>

    <proxy  proxyaddress="http://127.0.0.1:8888" />      

  </defaultProxy>

Here is a basic implementation of Custom Configuration Settings with nested collections in C# for future reference.  I'm sure I'll be using this a lot.

TestCustomConfig.zip (5.33 kb)