I've installed this on my own LibreELEC machine, but attempting to run Comskip gives an error:
If you like you can test Tvheadend nightly builds for LibreELEC some new build from here, it has comskip included (starting with 4.3-287-04.07.2017).
Completely untested from my side.
binary is then at /storage/.kodi/addons/service.tvheadend42/bin/comskip
syntax error: unexpected word (expecting ")")
thats due a wrong executable (RPi used at generic or similar)