Hi erictai, if you can't use the HQ option in the Slingplayer for Ipad, make sure that your Internet Viewing is set up properly.
This article may help you verify the type of connection that the Slingplayer is using.
I had the same problem. The only way I was able to fix it was to set up Internet viewing manually, I.e., I manually set it up in my router and then entered that info via setup through the sling setup program (not the internet web based program, but the one you can access via SlingPlayer for Windows). I found any time I set up internet viewing via the web based setup program it would be greyed out as you described. Hope this helps.