I have searched for a way to use Altova DiffDog as the merge tool for config and other xml files in Visual Studio 2012, TFS. The information I'm after is what command line codes to use in the "Configure User Tools" dialog.
Try Code Compare tool (from Devart). In the new 3.0 version, they have implemented a structural comparison of XML type files, is very useful for merge. It can automatically integrate into TFS.