Open logs is a pretty strong constraint on the AI. You'd have to restrict yourself to strategies that wouldn't make everyone you know hate you, prevent you from getting hired in the future, etc.
Log in to IRC as "Boxed_AI" and "AI_Gatekeeper". Conduct experiment. Register a throw-away LessWrong account. Post log. Have the Gatekeeper post with their normal account, confirming the validity.
That at least anonymizes the Boxed_AI, who is (I presume) the player worried about repercussions. I wouldn't expect the AI to have a similar-enough style to really give away who it was, although the gatekeeper is probably impossible to anonymize because a good AI will use who-they-are as part of their technique :)
Update 2013-09-05.
I have since played two more AI box experiments after this one, winning both.
Update 2013-12-30:
I have lost two more AI box experiments, and won two more. Current Record is 3 Wins, 3 Losses.