How can you use PowerShell's . (dot) notation to walk through elements with periods in the element name?
Alternatively, you can use variables:
$subproperty = 'System.Web'$webAppXml.configuration.$subproperty
I find this to be the most useful technique, because it lets me switch properties easily.
BTW, you can use the same trick to get to a method definition, and not run it.
Hope this Helps