When mkvirtualenv command, how to set Python ver?
There's no easy answer to your question. This project isn't the issue, though. If you find an answer, let us know. Places to start:
Running multiple versions of python on Windows is difficult. See http://stackoverflow.com/questions/4583367/how-to-run-multiple-python-version-on-windows.
Virtualenv supports passing in different a different python version via an undocumented -p switch. See http://pythoncentral.org/setting-up-the-python-environment-with-virtualenv/. But I've never tested that on Windows. You'd have to solve #1 first. You should be able to pass parameters to virtualenv via mkvirtualenv, so my project isn't the problem.