Cross domain autologin for just mapped domains of current site?

Is this possible or just for all sites? Don't really need users waiting minutes to be logged in to the 100+ domains on my network. However cross domain login for the users own 1-2 mapped domains would be ideal to guarantee compatibility with plugins that rely on a login cookie to view front end. For security reasons I need to force logins and administration to original domain which breaks plugins like under construction by Jeremy Massel that allow visibility of a hidden site when logged in. This of course doesn't work when logging in to and trying to view