Activate digital camera from desktop application

Program an application to activate a digital camera to take a picture when a certain action takes place within a desktop application. What I would like to do is have a digital camera poised over a work station and each time the operator clicks on a button in the desktop application, the camera would take a picture of the work area. Specifically, I want to take a picture of the box sitting on a shipping scale so each time the operator clicks "Process Shipment" in the UPS Worldship application on his desktop, the camera would be triggered to take a picture of the box and the label on the box. This could also be a still-frame image from a web-cam or USB connected camera.