DWM configuration for Gentoo Linux

Dynamic Window Manager.md

Enable Touchpad tapping

I think you don't need to build dwm youself and write a special script which setup xinput properties. You can just use Xorg configuration file instead

Create a file /etc/X11/xorg.conf.d/30-touchpad.conf that contains this:

Section "InputClass"
    Identifier "touchpad catchall"
    Driver "libinput"
    Option "Tapping" "on"
EndSection

and restart Xorg.