[ltp] trackpoint middle click scrolling went away once again

[Dot Deb]

Some time ago (some weeks) trackpoint middle click scrolling went away
once again under debian/sid on a x200s.
I read a past thread on this but now I'm even more confused about the
recent changes in xorg, udev & c.

Once I used xorg.conf, then I used the fdi, then I moved to some udev
rule ... now I'm done!
Is there any up-to-date guide on how to set up the trackpoint scrolling?

Alternatively, is there anybody so kind to explain me the situation?

Alberto