TeXworks

By default, choosing the ConTeXt option from the drop-down executes

 texmfstart texexec <filename>

which executes ConTeXt using pdfTeX; the XeConTeXt option executes

 texmfstart texexec --xtx <filename>

which uses XeTeX.

Adding an option to use ConTeXt with LuaTeX

• In the menu select Edit > Preferences...
• Go to the Typesetting tab
• On the Typesetting tab, the "+" button at the bottom right lets you add new compilation options.
• To typeset with MkII and the LuaTeX engine:
  • Program: texmfstart
  • Parameters: texexec --lua $fullname
• To typeset with MkIV (which always uses LuaTeX):
  • Program: mtxrun
  • Parameters: --script context --synctec $fullname