The remote central locking on this car is Infa-Red, via a sensor in the rear
view mirror/headlining unit, along with reading light etc.

If it is the remote function that you are looking to disable then all you
need to do is tape over the dome sensor.

If you want to deactivate the key driven central locking then you will have
to dig a little deeper.

There is a central locking relay unit (I'm pretty sure it is under the dash
in or next to the fuse box.  Operate the central locking via the remote
control whilst insode the care listening carefully for the clicking of the
relay/control unit.  Put your finger on the 'target' unit (probably a small
1 inch square plue or metal silver 'box' to feel for vibration.

You should be able to gently pull the unit out.

I could give you wire colours but unless you are prepared to get behind
these devices they will not help you much as you really need to be able to
see the back of all units and fuse box to be absolutely sure you are on the
right device.

Good luck :-)

Nick /////