Problem:

I have xml transforms I want to preform on build not only on publish. I also want an easy way to transform my config files during my team build.  Finally I want to use it on app.configs in WPF applications as well.

Solution:

Use SlowCheetah XML Transforms package.  You can install it from the Extension Manager in Visual Studio. 

Explanation:

SlowCheetah enables you to transform your app.config or any other XML file based on the build configuration. It also adds additional tooling to help you create XML transforms.

 http://visualstudiogallery.msdn.microsoft.com/69023d00-a4f9-4a34-a6cd-7e854ba318b5