I can't download the protected pages of a website. By looking at the cookie of
the website, I noticed that it's changing each time I access another page in
my browser. Most of the information stays the same, but one value is always
changing. The post request submits this value from the cookie. There is no
authentication information in the URL. 
Is there a way to tell HTTrack to behave the same way? 

To clarify, let's say we've got Browserclient(B), Server(S), Pages(P1,P2),
Values(V1, V2), Cookie(Ck), Request(Rq) and Response(Rs). After logon at this
site the communication is like this: 
B->Rq(V1 fom Ck)->S(P1)->Rs(P1, V2)->B(V2 into Ck)->Rq(V2 from Ck)->S(P2)...
and so on.