jplx-gn2 ~ # emerge --search evemu
  
[ Results for search key : evemu ]
Searching...

*  app-misc/evemu [ Masked ]
      Latest version available: 2.7.0
      Latest version installed: [ Not Installed ]
      Size of files: 498 KiB
      Homepage:      https://www.freedesktop.org/wiki/Evemu/
      Description:   tools and bindings for kernel evdev device emulation, data capture, and replay
      License:       LGPL-3 GPL-3

[ Applications found : 1 ]

######## Comment: this package is masked, which appears to mean that it should not be installed. Are libinput and evdev not mutually exclusive?
In the gentoo libinput wiki page, in the Troubleshooting section, it is implied that evdev should no longer be installed if libinput is.

jplx-gn2 ~ # emerge --ask --pretend app-misc/evemu

These are the packages that would be merged, in order:

Calculating dependencies... done!
[ebuild  N    ~] app-misc/evemu-2.7.0  USE="-python -static-libs" PYTHON_TARGETS="python2_7" 

The following keyword changes are necessary to proceed:
 (see "package.accept_keywords" in the portage(5) man page for more details)
# required by app-misc/evemu (argument)
=app-misc/evemu-2.7.0 ~amd64

######## Comment: In the man page, package.accept_keywords appears to be used for "unstable packages". Not sure what to do here.

jplx-gn2 ~ # ls -l /sys/class/input/event*
lrwxrwxrwx 1 root root 0 Apr  5 19:47 /sys/class/input/event0 -> ../../devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0D:00/input/input0/event0
lrwxrwxrwx 1 root root 0 Apr  5 19:47 /sys/class/input/event1 -> ../../devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0C:00/input/input1/event1
lrwxrwxrwx 1 root root 0 Apr  5 19:47 /sys/class/input/event2 -> ../../devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/LNXVIDEO:00/input/input2/event2
lrwxrwxrwx 1 root root 0 Apr  5 19:47 /sys/class/input/event3 -> ../../devices/platform/i8042/serio0/input/input3/event3
lrwxrwxrwx 1 root root 0 Apr  5 19:47 /sys/class/input/event4 -> ../../devices/pci0000:00/0000:00:1f.3/sound/card0/input4/event4
lrwxrwxrwx 1 root root 0 Apr  5 19:47 /sys/class/input/event5 -> ../../devices/pci0000:00/0000:00:1f.3/sound/card0/input5/event5
lrwxrwxrwx 1 root root 0 Apr  5 19:47 /sys/class/input/event6 -> ../../devices/pci0000:00/0000:00:1f.3/sound/card0/input6/event6
lrwxrwxrwx 1 root root 0 Apr  5 19:47 /sys/class/input/event7 -> ../../devices/pci0000:00/0000:00:1f.3/sound/card0/input7/event7
lrwxrwxrwx 1 root root 0 Apr  5 19:47 /sys/class/input/event8 -> ../../devices/pci0000:00/0000:00:1f.3/sound/card0/input8/event8
lrwxrwxrwx 1 root root 0 Apr  5 19:47 /sys/class/input/event9 -> ../../devices/pci0000:00/0000:00:1f.0/PNP0C09:00/VPC2004:00/input/input9/event9

jplx-gn2 ~ # udevadm info /sys/class/input/event0
P: /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0D:00/input/input0/event0
N: input/event0
E: DEVNAME=/dev/input/event0
E: DEVPATH=/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0D:00/input/input0/event0
E: ID_INPUT=1
E: ID_INPUT_SWITCH=1
E: ID_PATH=acpi-PNP0C0D:00
E: ID_PATH_TAG=acpi-PNP0C0D_00
E: LIBINPUT_ATTR_LID_SWITCH_RELIABILITY=reliable
E: LIBINPUT_DEVICE_GROUP=19/0/5:PNP0C0D/button
E: MAJOR=13
E: MINOR=64
E: SUBSYSTEM=input
E: TAGS=:power-switch:
E: USEC_INITIALIZED=118275690

jplx-gn2 ~ # udevadm info /sys/class/input/event1
P: /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0C:00/input/input1/event1
N: input/event1
E: DEVNAME=/dev/input/event1
E: DEVPATH=/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0C0C:00/input/input1/event1
E: ID_INPUT=1
E: ID_INPUT_KEY=1
E: ID_PATH=acpi-PNP0C0C:00
E: ID_PATH_TAG=acpi-PNP0C0C_00
E: LIBINPUT_DEVICE_GROUP=19/0/1:PNP0C0C/button
E: MAJOR=13
E: MINOR=65
E: SUBSYSTEM=input
E: TAGS=:power-switch:
E: USEC_INITIALIZED=118292358

jplx-gn2 ~ # udevadm info /sys/class/input/event2
P: /devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/LNXVIDEO:00/input/input2/event2
N: input/event2
E: DEVNAME=/dev/input/event2
E: DEVPATH=/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/LNXVIDEO:00/input/input2/event2
E: ID_INPUT=1
E: ID_INPUT_KEY=1
E: ID_PATH=acpi-LNXVIDEO:00
E: ID_PATH_TAG=acpi-LNXVIDEO_00
E: LIBINPUT_DEVICE_GROUP=19/0/6:LNXVIDEO/video
E: MAJOR=13
E: MINOR=66
E: SUBSYSTEM=input
E: TAGS=:power-switch:
E: USEC_INITIALIZED=118292251

jplx-gn2 ~ # udevadm info /sys/class/input/event3
P: /devices/platform/i8042/serio0/input/input3/event3
N: input/event3
S: input/by-path/platform-i8042-serio-0-event-kbd
E: DEVLINKS=/dev/input/by-path/platform-i8042-serio-0-event-kbd
E: DEVNAME=/dev/input/event3
E: DEVPATH=/devices/platform/i8042/serio0/input/input3/event3
E: ID_BUS=i8042
E: ID_INPUT=1
E: ID_INPUT_KEY=1
E: ID_INPUT_KEYBOARD=1
E: ID_PATH=platform-i8042-serio-0
E: ID_PATH_TAG=platform-i8042-serio-0
E: ID_SERIAL=noserial
E: LIBINPUT_ATTR_KEYBOARD_INTEGRATION=internal
E: LIBINPUT_DEVICE_GROUP=11/1/1:isa0060/serio0
E: MAJOR=13
E: MINOR=67
E: SUBSYSTEM=input
E: TAGS=:power-switch:
E: USEC_INITIALIZED=118452361

jplx-gn2 ~ # udevadm info /sys/class/input/event9
P: /devices/pci0000:00/0000:00:1f.0/PNP0C09:00/VPC2004:00/input/input9/event9
N: input/event9
S: input/by-path/pci-0000:00:1f.0-platform-VPC2004:00-event
E: DEVLINKS=/dev/input/by-path/pci-0000:00:1f.0-platform-VPC2004:00-event
E: DEVNAME=/dev/input/event9
E: DEVPATH=/devices/pci0000:00/0000:00:1f.0/PNP0C09:00/VPC2004:00/input/input9/event9
E: ID_INPUT=1
E: ID_INPUT_KEY=1
E: ID_PATH=pci-0000:00:1f.0-platform-VPC2004:00
E: ID_PATH_TAG=pci-0000_00_1f_0-platform-VPC2004_00
E: KEYBOARD_KEY_08=f20
E: KEYBOARD_KEY_0d=rfkill
E: KEYBOARD_KEY_42=f23
E: KEYBOARD_KEY_43=f22
E: LIBINPUT_DEVICE_GROUP=19/0/0:ideapad
E: MAJOR=13
E: MINOR=73
E: SUBSYSTEM=input
E: TAGS=:power-switch:
E: USEC_INITIALIZED=118322382

jplx-gn2 ~ # 

jplx-gn2 ~ # udevadm info /sys/class/input/event4
P: /devices/pci0000:00/0000:00:1f.3/sound/card0/input4/event4
N: input/event4
E: DEVNAME=/dev/input/event4
E: DEVPATH=/devices/pci0000:00/0000:00:1f.3/sound/card0/input4/event4
E: ID_INPUT=1
E: ID_INPUT_SWITCH=1
E: ID_PATH=pci-0000:00:1f.3
E: ID_PATH_TAG=pci-0000_00_1f_3
E: LIBINPUT_DEVICE_GROUP=0/0/0:ALSA
E: MAJOR=13
E: MINOR=68
E: SUBSYSTEM=input
E: TAGS=:power-switch:
E: USEC_INITIALIZED=118302751

jplx-gn2 ~ # udevadm info /sys/class/input/event5
P: /devices/pci0000:00/0000:00:1f.3/sound/card0/input5/event5
N: input/event5
E: DEVNAME=/dev/input/event5
E: DEVPATH=/devices/pci0000:00/0000:00:1f.3/sound/card0/input5/event5
E: ID_INPUT=1
E: ID_INPUT_SWITCH=1
E: ID_PATH=pci-0000:00:1f.3
E: ID_PATH_TAG=pci-0000_00_1f_3
E: LIBINPUT_DEVICE_GROUP=0/0/0:ALSA
E: MAJOR=13
E: MINOR=69
E: SUBSYSTEM=input
E: TAGS=:power-switch:
E: USEC_INITIALIZED=118332168

jplx-gn2 ~ # udevadm info /sys/class/input/event6
P: /devices/pci0000:00/0000:00:1f.3/sound/card0/input6/event6
N: input/event6
E: DEVNAME=/dev/input/event6
E: DEVPATH=/devices/pci0000:00/0000:00:1f.3/sound/card0/input6/event6
E: ID_INPUT=1
E: ID_INPUT_SWITCH=1
E: ID_PATH=pci-0000:00:1f.3
E: ID_PATH_TAG=pci-0000_00_1f_3
E: LIBINPUT_DEVICE_GROUP=0/0/0:ALSA
E: MAJOR=13
E: MINOR=70
E: SUBSYSTEM=input
E: TAGS=:power-switch:
E: USEC_INITIALIZED=118282464

jplx-gn2 ~ # udevadm info /sys/class/input/event7
P: /devices/pci0000:00/0000:00:1f.3/sound/card0/input7/event7
N: input/event7
E: DEVNAME=/dev/input/event7
E: DEVPATH=/devices/pci0000:00/0000:00:1f.3/sound/card0/input7/event7
E: ID_INPUT=1
E: ID_INPUT_SWITCH=1
E: ID_PATH=pci-0000:00:1f.3
E: ID_PATH_TAG=pci-0000_00_1f_3
E: LIBINPUT_DEVICE_GROUP=0/0/0:ALSA
E: MAJOR=13
E: MINOR=71
E: SUBSYSTEM=input
E: TAGS=:power-switch:
E: USEC_INITIALIZED=118282350

jplx-gn2 ~ # udevadm info /sys/class/input/event8
P: /devices/pci0000:00/0000:00:1f.3/sound/card0/input8/event8
N: input/event8
E: DEVNAME=/dev/input/event8
E: DEVPATH=/devices/pci0000:00/0000:00:1f.3/sound/card0/input8/event8
E: ID_INPUT=1
E: ID_INPUT_SWITCH=1
E: ID_PATH=pci-0000:00:1f.3
E: ID_PATH_TAG=pci-0000_00_1f_3
E: LIBINPUT_DEVICE_GROUP=0/0/0:ALSA
E: MAJOR=13
E: MINOR=72
E: SUBSYSTEM=input
E: TAGS=:power-switch:
E: USEC_INITIALIZED=118282536

jplx-gn2 ~ #