Hi there,
At the recent teaching weekend in Bridge of Allan, Fin Moore brought along a pressure meter (yes, it cam from the US originally, reading in inches of water gauge) which worked exactly as the manometer. We all tried it and very helpful it was too. The way it was connected was to take off the top section of a drone and replace it with the plastic tubing which connected to the meter (or in your case, the manometer). The point about it was that we were to play normally, with chanter and two drones, and watch how steady the pressure was or wasn't. Fin's was and mine wasn't.
George