[mod_python] preserving the session across subdomains

Hello,

I have a couple of domains that could be hosted in the same or even
different machines, e.g. sub1.mydomain.com and sub2.mydomain.com and
in of them I initiate a session using the Session module. I would like
to maintain the session across these two domains so when a surfer goes
from one to another his session remains intact. Is it possible to do
this with the Session module? or do I need to use Cookies explicitly?

Thanks,
Haris Lekatsas