rerequisites

wayland, including wayland-scanner and the base protocols
libxkbcommon
libtls (either from libressl, or libretls)
A compositor making use of wlroots, or (on an experimental basis) KDE, or (if all else fails) the willingness to run questionable networking utilities with the privileges to access /dev/uinput
wl-clipboard for clipboard support (only works on wlroots, not KDE/GNOME)

...

In my case, a 'uinput' group is created, and a udev rule is used to modify the permissions appropriately:

/etc/udev/rules.d/49-input.rules, in my case

KERNEL=="uinput",GROUP:="uinput",MODE:="0660"

From here, one could assign one's users to this group, but doing so would open up uinput to every program, with all the potential issues noted in the first paragraph. The safest approach is probably setgid:

as root -- adjust path as needed

chown :uinput waynergy chmod g+s waynergy

If this doesn't still doesn't seem to work (as in #38) be sure that the uinput module is loaded properly. This might be done by creating a file /etc/modules-load.d/uinput.conf with the contents of uinput

This is compared to just installing synergy which takes 7 seconds. I'm not sure why anyone imagines this is a credible alternative.