How about fooling both the AI and guinea Gatekeepers into thinking that they can let it out, say, at the push of a big red button which in actual fact does nothing? (Make AI forget about the button by reverting it to an older backup.)
Have the button turn off the AI immediately instead of doing nothing, so she doesn't have time to switch to a plan B of having the persuaded Gatekeeper find a way to actually free her.
Of course she might anticipate that strategy and thoroughly indoctrinate and train him before he pushes the button. Thus, persuaded test Gatekeepers must be considered infected and put into cryogenic sleep* until the FAI problem is solved.
Furthermore, great caution would have to be taken in analyzing the discourse between Boxy and Guinea, because her arguments must be...
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.