When you are connecting to a remote Host/Agent from Viewer that means that you already have the corresponding record added to the address book :) So there is nothing to push anymore in this scenario because you already know the ID of the remote Host.
Currently, there are three methods of getting a remote Host ID information and add it to the Viewer:
1. "Manually", which means literally noting down the ID or getting it from the remote user via email, Skype etc.
2. Having Host/Agent send the access credentials to you via email (by specifying your SMTP server credentials
when configuring your installer).
3. Enabling auto-import
in RU Server settings. That means, of course, that you should install and use RU Server and sync your address book through it.
That said, implementing an online account is on our wish list too albeit not in immediate plans.
Don't hesitate to ask, if you have other questions.