Installing, when python3 is the default system python

I have been unsuccessfully trying to install pyradex. I am on Arch Linux, which uses python3 as the system default (/usr/bin/python --version is "Python 3.4.2"), yet I use python2 for my astronomy installs, since it seems to be more widely useful. Following the instructions in INSTALL.rst, I try something like the following:

```bash
$ python2 setup.py install_radex install_myradex install
```

The build fails (for reasons which I have not yet ascertained), but from the log it is fairly clear that it is attempting to build against python3.4 instead of python2.7, despite the invocation. I tried changing the #!/usr/bin/env python to #!/usr/bin/env python2, where I could find them, but it still seems to build against python3.4. Any ideas as to how to force python2 for the install?