I would probably try to use the "O" option in order to adapt the mirror path
accordingly as well as "r" option to control the mirror depth, which in that
case probably should be the smallest possible.
And create a script, which runs per your link such a restricted HTTrack
command. This means also to utilize the command line version of it.
You find more infos here: <http://www.httrack.com/html/fcguide.html>