Sorry for my ignorance about a technical or legal issue, 
but most sites with useful information you would like to 
take a snapshot of require you to logon.

As far as I know, such sites make use of cokkies but I 
don't think it's a realistic solution to provide HTTrack 
with either an automatic analisys capability on when and 
where and how to logon, or an interactive system for it. 

So how about importing or reusing ready-made cokkies in the 
browser cache?