I actually have the need for this right now.
Besides having the general server description that
every item (Calendar, Contacts, Notes & Tasks) has to
connect to, you should allow the server information to
be entered on a per item basis.
i.e. Calendar could sync to a different server/remote
end-point than the Contacts.
I have a customer who would like to sync all of their
employees (small company) to the same Calendar and
Contacts, and have them sync to their own Notes and Tasks.
sourceforge@shadowwareservices.com