ConTeXt Standalone/Implementation
splitting binaries
files.lst : # common ... ... #luatex ... ... #xetex ... ... #pdftex ... ...
i can then use that (will make a script) that will install what is needed
mtxrun --script install --engine=xetex --platform=macosx-intel
and such (is we make luatex 'common' we have a scripting machinery)