Do you have an actuator in the door already, or do you need to add that too?
Our Discovery came with a key fob and there was already an actuator in the door to move the lock mechanism. I then installed one of these https://www.keyless.com/ke-1700/
so that we did not need to carry the key fob.
I had taken apart the door latch at one point, the actuator is just a generic power lock solenoid.
The keyless website I linked above has key fobs that you can use in addition to the keypad.