Download the sources from here : <http://packages.debian.org/stable/web/httrack>
(Download links are towards the right side of the page)

Once you have downloaded httrack_x.xx.x.orig.tar.gz.
Untar the downloaded package

Go to the extracted folder on the command line.
eg. : cd ~/Downloads/httrack-3.46.1

Run the following commands:
./configure 
make
make install

P.S. You need to have XCode Dev tools, MacPorts installed