Try adding the conda-forge channel to your list of channels with this command:
conda config --append channels conda-forge
. It tells conda to also look on the conda-forge channel when you search for packages. You can then simply install the two packages with conda install slycot control
.
Channels are basically servers for people to host packages on and the community-driven conda-forge is usually a good place to start when packages are not available via the standard channels. I checked and both slycot and control seem to be available there.