You can add a proxy by doing the following on the newwatch.slingbox.com website (I recommend using IE on PC or Safari on Mac to do this):
- Click SlingBox Directory
- Click on Edit Proxy Settings (underneath the SlingBox Icon)
- Change Streaming Proxy from "none" to "use custom proxy"
- Enter the Proxy Server's IP Address, Port number and access credentials (if needed).
- Hit Save
If you use the desktop player app, the settings you apply on the website will also apply there (Sling, please fix this. We should be able to add a proxy from within the Desktop Player app)
Also, I recommend using a mobile device with the Slingplayer app to access your Slingbox. For some reason, which escapes me, the mobile apps have a much more stable stream in terms of speed and quality. (Even without a proxy, which they cannot use.)
I would have recommended the proxy service I use, but they no longer accept new sign ups.