Hi, thanks for posting.
Usually, it should be possible to add this to the config file for the test project (i.e. myproject.config). NCrunch specifically detects test project config files and will include them in the runtime environment by using them as the source of configuration for the test application domain.
There are some configuration settings (such as binding redirections) that can only be applied to the config file of the task host process itself (i.e. C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\Common7\IDE\Extensions\Remco Software\NCrunch for Visual Studio 2017\nCrunch.TaskRunner462.x86.TestHost.exe.config). I don't believe TraceSource is one of these.