Configuring XML with WiX

1Namespace.xml

<Wix XMLns="http:⁄⁄schemas.microsoft.com⁄wix⁄2006⁄wi"
     XMLns:util="http:⁄⁄schemas.microsoft.com⁄wix⁄UtilExtension">

2Util.xml

<util:XmlFile File="[INSTALLLOCATION]⁄Uploader.exe.config"  
  Id="config"  
  Action="setValue"
  Name="connectionString"                             
  ElementPath="⁄configuration⁄connectionStrings⁄add[\[]@connectionString[\]]"
  Value="TESTVALUE"
  ⁄>