I don't believe that 'virtualenv' library supports your usecase
(encapsulating
a full Python environment on a host without Python): it requires
an actual installation of the required version of Python to be
present on the system.
If 'python2.6' *is* present on your system, then you could try
downloading a 2.6-
compatible version and running its 'virtualenv.py' script directly,
e.g.:
---------------------------------- %<
-----------------------------
$ curl --location --output virtualenv-15.2.0.tar.gz \
https://github.com/pypa/virtualenv/tarball/15.2.0
$ tar xvfz virtualenv-15.2.0.tar.gz
$ cd pypa-virtualenv-61255cf/ # path differs for other releases
$ python2.6 virtualenv.py /path/to/virtualenv
---------------------------------- %<
-----------------------------
Note that I don't have a 'python2.6' on my system, so I couldn't
test the last line,
but it matches my memory, and the legacy docs[1]
Tres.
[1]
https://virtualenv.pypa.io/en/legacy/installation.html