Thanks for asking! To make a guest user for the SlingBox PRO you would need to go to setup.slingbox.com to register the email to this SlingBox.
This article below will further explain where to go to add the guest account:
If you have any other questions, feel free to respond or give us a call at 1-877-467-5464. We are open seven days a week, from 10:00am to 10:00pm EST.
The Sling Media Moderation Team
Which s/w are you using to access the SB-Pro, client ? (vs 1.5 or 2.0)
You can rerun the setup and add the "guest' or view only password on the password screen.
You can run the Setup Assistant on client 2.0. After login, go to "setup your Slingbox. The first page has password entries.
Using client 1.5, I think the password entries are on the dropdown menu item "Player, Sling Player Options". You can add/change the guest passwork local or remote, so long as you have the admin password.