Can conda install be used to install source-distributions (i.e. non-archived import packages that have a setup.py)?
As mentioned by vaiski, you can use pip and/or setup.py to build and install the package, but this method is not ideal because packages installed with pip and conda do not respect each other's dependencies.
Thus, if the source distribution includes a conda build recipe (meta.yaml), then you can created the anaconda archive on your own machine by using the conda-build tool:
$ conda build meta.yaml
Afterwards, you will have a local tar.gz of the build package with meta-data that conda can understand. This is what you download from the internet whenever you install a package using conda.
Finally, you can install the package you built locally using:
$ conda install --use-local