Reply to controller modification?

whats up djtt people.
I was believeing about fitting a vu meter(leds) from an old numark mixer to my midi controller. can this be easily done? i dont no much about electronics but i am handy when it comes to fabrication. it could probally be done easily by hooking it up between the output of the controller and the speakers using an external power source but how difficult or possible would it be to connect it to the controller internally?
has anyone done anything like this?
need some guidence thanks