Hhhhmmmm. Well, I believe that the cflogin is only available
to the application for which it is used within. You may have to
write your own login method, possibly saving a user's username and
password within the session scope (encrypted) that you then pass to
server B or C through the form scope when the user moves to those
servers. When a page is called on server B or C it then looks for
the presence of the form scope, copies the values to their session
scope, unencrypt the values to reauthenticate at the new server
(all in the background), and then move along with their business.
That's one idea, I'm sure there are probably several different ways
to handle this.