Thank you for posting in our online forums! I see you want to put over 500 Slingbox's under one account and you want to know if there is a way to do this without going through them one by one. To answer your question, they will all have to be setup under the email on the account one by one. However, if you already have set them up and you have the 32 digit Slingbox URL, you can add them all to your account that way. Please follow the link below to see how to add them to your directory.
Please reply back if you have any further questions.
Sling Media Moderation Team