I found thinking about slow ways to torture the person responsible for the mission while swearing loudly an effective tactic, but I imagine you have tried that!
Just before his health reaches 50% stop attacking him and pull both levers.
Resume attacking him and the instant his health reaches 50% he runs off to heal, you get perhaps 15 seconds to finish him off.
Wait more than 15 seconds and he will magically teleport into both booths one after the other.
Timing is crucial.
One of very few things I dislike about this game, wich I thoroughly enjoyed btw!
