To map the hardware buttons of your Pocket PC to Signal functions, tap on the File menu and select "Settings...". Once the settings screen is displayed, tap on the "Buttons" tab near the bottom of the screen.
This screen displays a list of all functions that may be associated with a hardware button on your device. To create a new association, double-tap on the function name within the list. The button column will then display a "Waiting..." message. Now you may push any hardware button on your device to map that button to the specified function.
To release a button, tap and hold on the function name it is assigned to and select "Release Button".