Could you use some blinders for your pair?
Roobasoft’s Concentrate ( or Anti-Social) is a bit like blinders that I use to put on the pony while hitching up the plow (and although I'm not that old - yes we used our pony to plow the garden).
It works by turning off applications that could distract either pair such as access to Facebook, Twitter, chat, mail, etc. allowing your to concentrate on the task at hand.
I can think of several people I've paired with that this would have increased productivity about 300%! It was a task just to keep them focused. Of course the asides and tangents I went down were all for the better - yea right!
10 Concentration Apps that will help you to Focus