Since a 2-restroom system serves our tiny lab, an immediate fix was required. We used what we had on hand (admittedly, this is probably the best place for a jerry-rigged fix outside of a hardware store) and here's the list:
If you want the other members of your office to be able to know what to do with the string, it might help to write a little note saying "PULL TO FLUSH" on it.
Feel free to go crazy with the note. Just make sure it's clear that people are supposed to pull up to flush. That'll lift the plunger and allow the toilet to flush.
For those of you who are prepared to say, "But most people don't have a lasercutter!", don't worry about it. A folded up sheet of paper will work just as well. Maybe some cardboard. Cardstock. Use a marker to draw on a pen cap. Get creative.