Add NTLM proxy authentication to urllib2

[looping]

Hi,
I have to make internet connections through an ISA proxy server that
use NTLM or Kerberos authorization method.
I've found a program in python called ntlmaps that act like a proxy and
could make the NTLM authentication, but you have to run it and make all
your connection through it, not an optimal solution.
So what I really need is an enhanced urllib2 that support NTLM or
Kerberos.
I've found that pywin32 could manage NTLM encryption with the sspi
module but I've no idea how to implement it in urllib2, NTLM
authentication use a 'Token dance' between client and server.

Anyone has an experience, a demo or an idea to share ?

Thanks.