Help with addition features to remote control

Hello guys, im a student who is doing a final year project. I want to add additional features like a spraying button on a car remote control for an sprayer mount on the car. Is it possible and how?

Caveat: To experiment on the car's electronics is to risk ruining something expensive.

The remote control broadcasts a code when you press this or that button.

There is the slimmest possibility that the manufacturer put spare unused codes in the brain of the remote. If you could discover the right combination of buttons to press, and/or the right sequence of button presses, you might transmit a code to activate your project. (This is only speculation.)

In addition you would have to construct radio wave detection circuitry in the car, to decode your broadcast, and turn on the sprayer.

It is too much of a stretch to hope that you can get the existing detection circuitry (in the car) to respond to your broadcast code, and send a signal to your spray mechanism (if you can find a spare output line).