Can conda install be used to install source-distributions (i.e. non-archived import packages that have a setup.py)?
Yes and no. You can not conda install per se. However, as the Conda documentation says, Conda ships with pip, so you should be able to pip install -e . your package. You can also install with traditional python setup.py [install|develop].
Remember to activate your Conda environment before installation if you're using one instead of site packages.