The Skyline tool and interactive tool documentation, however, is old but still current. We just haven't needed to change much recently.
If you have special requests you would like to see supported, please let us know.
As Brian notes, the current documentation for SkylineCmd or SkylineRunner can be found either by running these EXEs without arguments or with --usage, or you can also find the same documentation in the Skyline GUI at Help > Documentation > Command Line.
Good luck with implementing your external tool. Let us know how we can help.
--Brendan