My mistake, the html from dirhtml does not stop Httrack.  Entering
<file:///c:/dir.html> with 3 /'s doesn't work.  Entering <file://c:/dir.html>
with 2/'s does work, even though the links inside the html have 3 /'s. Go
figure.

Thanks for suggesting dirhtml.  It appears to be a good solution for what I
want to do.