title: How to load Configuration from a string
body: <p><strong>Update 1</strong> - The suggested approach won't work, because of I need to load the whole Config, it's a contract between my code and external call (see my questions). The technique won't work at least because of Configuration is sealed. </p>
  
  <p>I have and Xml string representing an entire config file as input and need to create an instance of <code>System.Configuration.Configuration</code> out of it for passing into an external routine, which performs:</p>
  
  <pre><code>ServiceModelSectionGroup.GetSectionGroup(configuration);
  </code></pre>
  
  <p>as part of its logic.</p>
  
  <p>Wonder if it's possible to do it w/out using a file system (Can't call App domain for any direct manipulations neither).</p>