We are using the following link format to display a Twitch channel in a lightbox on our site:
//www-cdn.jtvnw.net/swflibs/TwitchPlayer.swf?channel=example
is there anything I can specify in the request so that the player doesn’t link back to Twitch on click, or will I have to code in something after the fact if we want to block this?
No, this is the expected behaviour, and preventing it breaches the API Terms of Service:
You won't try to obstruct the click-through to the channel page or the ads on Twitch’s proprietary video player (“Twitch Player”).
http://www.twitch.tv/p/api_terms_of_service
ahh, thank you very much for the clarification!