Assuming you mean on the coach, and not in the store...
it'll be screwed into an airline, fitting, valve, but it has wires attached to it.
Air piping and wires don't usually mix, except for the switches, brake light and low air warning.
luvrbus will know better where someone may have made an easier modification to an Eagle, and added one elsewhere.
Blindly, I'd be checking the plumbing under the floor, under the driver, closely watching the brake pedal plumbing, and following that rearward.
Do you know the routing of the brake light wiring? Which junction box it may be in?
May not be any provision in the front to wire one...?
happy coaching!
buswarrior