Maybe you want to use twill. It’s quite easy to use and should be able to do what you want.
It will look like the following:
from twill.commands import *
go('http://example.org')
fv("1", "email-email", "blabla.com")
fv("1", "password-clear", "testpass")
submit('0')
You can use showforms()
to list all forms once you used go…
to browse to the site you want to login. Just try it from the python interpreter.