For those that may find it useful: I wanted to configure IIS such that the default.aspx is the first default document for the web server. Here is the script if that's what you want to do:
 #requires -RunAsAdministrator $file = "default.aspx" $baseFilter = "/system.webServer/defaultDocument/files" $filter = "{0}/add[@value='{1}']" -f $baseFilter,$file $fileExists = $null -ne (Get-WebConfigurationProperty $filter -Name ".") $updateConfig = -not $fileExists if ( $fileExists ) { $firstValue = Get-WebConfiguration "$baseFilter/*" | Select-Object -ExpandProperty value -First 1 $updateConfig = $firstValue -ne $file if ( $updateConfig ) { Clear-WebConfiguration $filter -Verbose } } if ( $updateConfig ) { Add-WebConfiguration $baseFilter -AtIndex 0 -Value @{value = $file} -Verbose } 
 The script checks if default.aspx is set as a default document. If default.aspx is a default document, it checks if it's first in the list. If default.aspx is in the list but not first, the script removes it. If default.aspx is not set as a default document or it's not first in the list, the script adds it as the first in the list.
 The above script is the IIS GUI configuration equivalent of clicking the server node, double-clicking Default Document in the right pane, and moving default.aspx to the first position (or adding it in the first position if it's not in the list).