How to install systemd-independent udisks2 and policykit before removing systemd from a Debian jessie/sid installation

Add additional repositorys to /etc/apt/sources.lst . From Devuan:

or

depending on wether you have jessie or sid.

You also need packages from max2344, there are only packages for sid, but you can use them in jessie as well:

Reload your repositories by using synaptic or

 # aptitude update

Install the following packages from the first repository:

 udisks2 libudisks2-0 cgmanager libcgmanager0

Optional: To stop complaints about missing keys you can install devuan-keyring.

Optional: To give the packages from devuan a higher preference you can install devuan-baseconf.

Install the following packages from the second repository:

 libpolkit-agent-1-0 libpolkit-backend-1-0 libpolkit-gobject-1-0 policykit-1

Now you can purge systemd while still having a working udisks2 and policykit.