The pointer acceleration settings that libinput exposes to your desktop environment may not provide a range of values what would satisify your needs, and you may need to apply a more radical adjustment.

This is where hwdb comes in handy. It is a way to define device-specific overrides for the sensitivity value. The trackpoint hwdb file shipped with systemd, however, seems to contain outdated information, since the PONTINGSTICK_CONST_ACCELL is ignored by libinput as of this commit. The POINTINGSTICK_SENSITIVITY still has an effect: it seems to define the device sensitivity, i.e., the less sensitive the device is, the more reactive your pointer will become. So for more speed with less pressure on the trackpoint, decrease POINTINGSTICK_SENSITIVITY. (At least this is how it behaves on my hardware.)

Apart from that, the systemdb hwdb file contains concise instructions on creating a new hwdb entry, and I won’t repeat it here.

Note that in the near future (libinput version 1.12) the format of the configuration will change and will not use udev anymore. For the time being though, here’s my /etc/udev/hwdb.d/71-pointingstick-local.hwdb:

evdev:name:AlpsPS/2 ALPS DualPoint Stick:dmi:bvn*:bvr*:bd*:svnLENOVO:pn20DDS00H00:pvrThinkPadE450:*

The version of libinput on my system is 1.11.0.