You don't disconnect anything to do with the key central locking, this system needs to keep working.

You just mount a solenoid in the drivers side door and connect this to the locking rod, then wire up the keyless entry module.

How it works is, you push the button on the remote, it then activates the solenoid you fitted in the drivers door. This solenoid then moves the locking rod (just like you would do if you are manually locking or unlocking the vehicle). This then allows the genuine central locking to lock or unlock the other doors.

It doesn't matter if the Keyless entry kit comes with four solenoids you only need to fit one.

The keyless entry system should also be able to be connected to the indicator lights.

Personally I would also not get a keyless entry kit that has the automatic door locking function, I found this a real pain when out camping.