Here it is workable config.
Ricardo Wurmus said, there is actual manual in every commit. Here it is how to build html manual from your guix (or use info guix instead)
After last week's changes to how xorg configuration works, but I still
have some problems with the touchpad. Essentially, the extra-config
seems to have no effect.
1. The Tapping option does not work.
2. The HorizontalScrolling option does not work. Strangely, the
documentation[0] says that "HorizontalScrolling" *disables* horizontal
scrolling. I've tried it both ways.
3. The DisableWhileTyping option does not work. This actually never
worked, even before the change.
I've attached my config.scm file.
Luther