> In other words, what is the best way to get a whole site 
> and also a single page in the same -O directory ?
If you just need to update ONE pagen this is not totally 
obvious do to - the best way IMHO:

1. Patch the hts-cache/new.ndx file and devalidate the 
entry ; such as:
cat hts-cache/new.ndx | sed -e 's_/html/page1.html_XXX_g' > 
_tmp && mv -f _tmp hts-cache/new.ndx
2. Use the --continue flag in httrack

Note: for the 1., use either a Linux/Un*x system, or use 
cygwin with windows (www.cygwin.com)