> OK I'll try to do what I need. Could you just point me to 
> where to start? I was looking to the sources and well - 
all 
> the comments are in French ;-) I couldn't understand 
them. 
> Would it be possible to provide some short description 
for 
> them?
Hum, I'll have to document a bit more the API one day.

First take a look at lib/example.c, it can give you some 
interesting hints. 
The naming functions is located in htsname.c, in the 
url_savename() routine:

int url_savename(
char* adr_complete,  /* address (www.foo.com) */
char* fil_complete,  /* file (/foo/index.html) */
char* save,          /* target to generate */
char* former_adr,    /* address if moved during test */
char* former_fil,    /* file if moved during test */
char* referer_adr,   /* referer address if .. */
char* referer_fil,   /* referer file if .. */
httrackp* opt,       /* option settings */
lien_url** liens,    /* current link heap */
int lien_tot,        /* number of links in heap */
lien_back* back,     /* internal background download */
int back_max,        /* background size */
cache_back* cache,   /* internal cache */
hash_struct* hash,   /* filenames hashtable */
int ptr,             /* current position */
int numero_passe     /* reserved */
);

You just have to hack this function ; for example before 
line 628, before the loop which forms the filename 
according to the build structure settings. You have to 
create in the 'save' (char*) variable the filename, from 
the adr_complete and fil_complete address and filename.
Then, just leave the rest of the process (line 810) to 
handle collisions, and other things.

I'll add a wrapper which will simplify that in the future ; 
that is, just after (line 810) the 'save' initialization, 
an optional handler to modify it.