> which options do I need to syncronize 
> server.com/images/ with lets say home/mirror/images/? 
With 
> only one connection, a standard user-agent 
like "Mozilla/4.0 
> (compatible; MSIE 6.0; Windows NT 5.1)" and a maximum of 
> 25kb/s download?
You can only update a complete project. To do so:

cd <your directory>
httrack --update --sockets=1 --user-agent "Mozilla/4.0 
compatible; MSIE 6.0; Windows NT 5.1)" --max-rate=25000