Yes. You want to use DC not AC. If it's AC, you'll need a converter of some kind (at least a diode). You also need to know the voltage of the existing lights and the number of LEDs that you want to add. It is also helpful to know the color of the LEDs because different colors use a different "forward voltage". Then use the LED wizard to plug these numbers in and it will come up with the proper circuit for you. Just search for the LED wizard on the internet.