I understand that you are having some issues in order to adjust some iPad settings.
The rotation is a feature that you can adjust on the iPad settings. This specific feature has is not related to the Slingbox or the SlingPlayer application.
If you need to adjust it, you need to tap on the "Settings" button on your iPad. Then, you should be able to access the "Settings" screen. Go to "General" and look up for the "Use Side Switch to:" option and check the "Lock Rotation" window.
This little adjustment will allow you to take advantage of this specific feature, even when you are not using the SlingPlayer for iPad application.