yes you can. its easy and you can do it in a variety of ways
step one is to connect your midi controller and select it in the communications menu / midi setup
step two, add a "note on" watcher to your patch, and hit the button you would like to use. On the right side of the actor you see the values of the incoming midi note as you tap your button, change the values on the left side of the actor to these values and you now have a note on watcher that only listens to this button on your controller.
repeat for any other buttons, and use the "control watcher" for sliders and knobs.
if you want to use two buttons for on and off, connect them to a "trigger value" actor and trigger 100 to turn on and a 0 to turn off your projectors volume. if you want to use only one button to toggle, use the "sequential trigger".