ref: https://askubuntu.com/questions/1432996/adjust-trackpoint-speed-on-lenovo-p70-ubuntu-22-04
Here's what worked for me; your mileage may vary. First, find your device:
$ xinput list
⎡ Virtual core pointer id=2 [master pointer (3)]
⎜ ↳ Virtual core XTEST pointer id=4 [slave pointer (2)]
⎜ ↳ TPPS/2 IBM TrackPoint id=12 [slave pointer (2)]
⎜ ↳ Synaptics TM3053-004 id=11 [slave pointer (2)]
⎜ ↳ ELAN Touchscreen id=9 [slave pointer (2)]
...
On my system, I see it as TPPS/2 IBM TrackPoint. Next, find the acceleration property:
$ xinput list-props 'TPPS/2 IBM TrackPoint' | grep Accel
libinput Accel Speed (342): 0.000000
libinput Accel Speed Default (343): 0.000000
libinput Accel Profiles Available (344): 1, 1
libinput Accel Profile Enabled (345): 1, 0
libinput Accel Profile Enabled Default (346): 1, 0
Here, I see it as Accel Speed (342), and the 342 is what I need. After some experimentation, I was able to determine that the value, by default 0.000000 is expected to be in the range [-1, 1]. For me, -0.2 ended up being a good speed:
$ xinput set-prop 'TPPS/2 IBM TrackPoint' 342 -0.2
