NUnit Test Generator includes a seperate command line tool for generating code or unit tests as part of your build process.  You can generate test stubs for individual files or project files.  All the parsing options are there as well.

Here are the parameter names:
-input="input file path"
-output="output folder"
-template="template file path"
-testproject (optional)
-private (optional)
-internal (optional)
-protected (optional)

NUnit-Test-Generator-Console.exe -input="C:\MyInputFile.cs" -output="C:\My Documents" -template="C:\MyTemplate.cs"

NUnit-Test-Generator-Console.exe -template="C:\MyTemplate.cs" -output="C:\My Documents" -input="C:\*.cs" -testproject -private -internal -protected