Yep, this should do the trick for legal requirements I do believe.
One thing that could add to this, is including checkinstall. That way the program would be installed as a native slack package, that the user could easily remove at a later date.
Your approach here is similar to that of archlinux's AUR or gentoo portage-repos or *BSD ports repositories. As long as VL does not distribute a binary, VL is excluded from normal "hosting" or "distribution" clauses. Distributing instructions on how to _make_ a binary, is a totally free venue there.