On Mon, Sep 16, 2019 at 12:23:22AM +0200, Jan Wielkiewicz wrote:

> I've tried using the default Polish keyboard layout with SLiM and it
> doesn't seem to work

Hi,

In case you haven’t found the solution, yet, perhaps this snippet from
my config.scm will help you. You will need to trim it to adapt to your
circumstances.

  (services (cons* (service slim-service-type (slim-configuration
                                                (display ":0")
                                                (vt "vt7")
                                                (auto-login? #t)
                                                (default-user "w")
                                                (xorg-configuration
                                                  (xorg-configuration
                                                    (keyboard-layout (keyboard-layout "pl,cz"
                                                                                      "legacy,ucw"
                                                                                      #:options '("compose:menu,grp:caps_switch")))))))
  ;; skipped content
  ))

WŻ