How to create a button that sets a tag to 1 when button pressed but resets to 0 when unpressed.

You cannot achieve this using the predefined graphical component button.
You will need to design the button by your own using a rectangle.
Then add two different 'Send command' actions on the rectangle:
    - one to send the command (value = 1) on the "Mouse down" event
    - the other to send the command (value = 0) on the "Mouse up" event.

Uncheck the "Click" event and select the "Mouse down" or "Mouse up" event.