boost unit test with visual studio test adapter - set working directory

I'm trying to use boost unit tests, integrated into VS (2013) using the Visual Studio Test Adapter. My unit test tests a library that requires another DLL to be present in its working directory (it's linked by specifying the .lib in 'additional inputs' under linker settings, not through 'References'). I cannot adjust the global PATH (need to be able to reference multiple versions on one machine). Furthermore, my tests require some test data that is searched for relative to the current working directory.

Without the boost unit test adapter, I just set the working directory under 'debugging' or run the unit test executable from a command line, where the current working directory is obvious.

My question: how do I set the current working directory for the test to be run using the boost unit test adapter. I tried setting 'command' and 'working directory', and looked in the documentation of the adapter for a way to set the directory. None of that has helped. How is this supposed to work?