These files are used by XKB to generate my custom keyboard mappings.
It's an experimental work-in-progress that almost certainly has bugs because the XKB documentation is so arcane.
Drop the files into $XDG_CONFIG_HOME/xkb/, and execute something like the following line in a terminal:
xkbcomp -I$XDG_CONFIG_HOME/xkb/ $XDG_CONFIG_HOME/xkb/keymap/custom.xkb ${DISPLAY%%.*}
The changes take place immediately; you can use xev to verify.