oops. I found /etc/X11/xorg.conf.d/11-mouse.conf
Is this the place to configure this? Then I will send a patch.

11-mouse.conf contains:

Section "InputClass"
        # unknown
        Identifier      "IBM TPPS/2 TrackPoint"
        MatchVendor     "IBM Corp."
        MatchProduct    "TPPS/2 IBM TrackPoint"
        MatchIsPointer  "on"
        Driver  "evdev"
        Option  "EmulateWheel"  "on"
        Option  "EmulateWheelButton"    "2"
        Option  "YAxisMapping"    "4 5"
        Option  "Emulate3Buttons"    "on"
        Option  "EmulateWheelTimeout"    "200"
EndSection

but it does not seem to match. /proc/bus/input/devices:
I: Bus=0011 Vendor=0002 Product=000a Version=0000
N: Name="TPPS/2 IBM TrackPoint"
P: Phys=isa0060/serio1/input0
S: Sysfs=/devices/platform/i8042/serio1/input/input1
U: Uniq=
H: Handlers=mouse0 event1 
B: EV=7
B: KEY=70000 0 0 0 0
B: REL=3

lshal (no idea if there's a better way nowadays):
udi = '/org/freedesktop/Hal/devices/platform_i8042_i8042_AUX_port_logicaldev_input'
  info.capabilities = {'input', 'input.mouse'} (string list)
  info.category = 'input'  (string)
  info.parent = '/org/freedesktop/Hal/devices/platform_i8042_i8042_AUX_port'  (string)
  info.product = 'TPPS/2 IBM TrackPoint'  (string)
  info.subsystem = 'input'  (string)
  info.udi = '/org/freedesktop/Hal/devices/platform_i8042_i8042_AUX_port_logicaldev_input'  (string)
  input.device = '/dev/input/event1'  (string)
  input.originating_device = '/org/freedesktop/Hal/devices/platform_i8042_i8042_AUX_port'  (string)
  input.product = 'TPPS/2 IBM TrackPoint'  (string)
  input.x11_driver = 'evdev'  (string)
  linux.device_file = '/dev/input/event1'  (string)
  linux.hotplug_type = 2  (0x2)  (int)
  linux.subsystem = 'input'  (string)
  linux.sysfs_path = '/sys/devices/platform/i8042/serio1/input/input1/event1'  (string)


There is no trace of "IBM Corp.". So I commented out the MatchVendor line and that seems to work.
The Xaxis mapping still is missing.

Yeah, things have changed. :-(

Try to figure out with 'udevadm info -e' (check for ID_INPUT*) the right string
for vendor (probably ID_VENDOR).

Did we have Xaxis mapping in 11.2 for that touchpad?

P: /devices/platform/i8042/serio1/input/input1
E: UDEV_LOG=3
E: DEVPATH=/devices/platform/i8042/serio1/input/input1
E: PRODUCT=11/2/a/0
E: NAME="TPPS/2 IBM TrackPoint"
E: PHYS="isa0060/serio1/input0"
E: EV==7
E: KEY==70000 0 0 0 0
E: REL==3
E: MODALIAS=input:b0011v0002p000Ae0000-e0,1,2,k110,111,112,r0,1,amlsfw
E: SUBSYSTEM=input

P: /devices/platform/i8042/serio1/input/input1/event1
N: input/event1
S: char/13:65
S: input/by-path/platform-i8042-serio-1-event-mouse
E: UDEV_LOG=3
E: DEVPATH=/devices/platform/i8042/serio1/input/input1/event1
E: MAJOR=13
E: MINOR=65
E: DEVNAME=/dev/input/event1
E: SUBSYSTEM=input
E: ID_INPUT=1
E: ID_INPUT_MOUSE=1
E: ID_SERIAL=noserial
E: ID_PATH=platform-i8042-serio-1
E: DMI_VENDOR=LENOVO
E: DEVLINKS=/dev/char/13:65 /dev/input/by-path/platform-i8042-serio-1-event-mouse

Setting MatchVendor to "LENOVO" does *not* work, only not setting it at all works for me (but I might be missing something).

in 11.2 we had Xaxis:
(**) Option "YAxisMapping" "4 5"
(**) TPPS/2 IBM TrackPoint: YAxisMapping: buttons 4 and 5
(**) Option "XAxisMapping" "6 7"
(**) TPPS/2 IBM TrackPoint: XAxisMapping: buttons 6 and 7

Ok. Let's do it that way (SR #38030).

Works well for me with the X11:Xorg package