You can use javascript to block httrack and any other webbot
but you won't be indexed.
You can use server side techniques but .htaccess will not be
helpfull in your case.

The most effective is usually to block any user (IP or
session) requesting too many pages or sending too many
requests instead of trying to fool a robot.
You can find useful information here :
<http://www.httrack.com/html/abuse.html#WEBMASTERS>
<http://www.garykeith.com/browsers/bad-bots.asp>
webmasterworld has many threads about blocking spiders and
spider traps (using perl, php, asp...)
you can look for web spider traps and and find solutions to
bandwidth usage abuse.
and in French
<http://www.1001bd.com/stop_aspirateurs/>
<http://www.toulouse-renaissance.net/c_outils/c_interdire_aspirateurs.htm>