How to get virtualenv for compiled python (missing pip/easy_install)?
From the docs on installing packages at https://packaging.python.org/tutorials/installing-packages/#ensure-you-can-run-pip-from-the-command-line there is a section on ensuring pip by running
/path_to_compiled_python/bin/python -m ensurepip --default-pip
which will install pip. You can then use it to install the virtualenv package with
/path_to_compiled_python/bin/pip install virtualenv