How do I fix a Package etex error?

If you see a typeset error message similar to

  ! Package etex Error: This package may only be run using an
  etex in extended mode.

this may be fixed by using PCTeXv6 in extended mode. To enable it, go to PCTeX's Typeset menu, select INITeX, select LaTeX, add an asterisk before the macro name (e.g. *latex.ltx), and click INITeX.

Keywords: eTeX, v6, install