You cannot set up a Slingbox 350 with the Slingplayer Application. To set up a Slingbox 350, you have to be on a PC or Mac that is on the same network as the Slingbox and navigate to Newwatch.Slingbox.com. The website should find the Slingbox and walk you through the setup process.
For a list of supported browsers and operating systems, check here:
Sling Media Forum Moderation Team