Here are the instructions on how to connect an aftermarket alarm to the factory central locking if you loose remotes or decide it's time for a change.

ok, normally there are two relays (6 wires) in the aftermarket alarm
(1)
NO
NC
Common
(2)
NO
NC
Common

wires you need to find

in the wiring harness(in the foot well going to the door):
plain white

in the driver's door:
plain black (make sure it is the one that runs to the door lock actuator, it'll be bundled with another 4 wires but I forget their colours)


How to do it:
1. run a couple of wires (speaker wire works well) into the door from the foot well
2. cut the black wire - if you haven't removed the battery, the doors might unlock.
3. connect the wires to either side of the black wire you just cut.
4. these two wires now get connected to the NC and common of one of the relays
(this is the unlocking section done)

5. splice onto the white wire and connect this to the NO contact of the second relay
6. connect the common from the second relay to ground
(this is the locking section done

And its that easy.

NC  ----- | ------- (black that was cut)
Com \---- | ------- (black that was cut)
NO  ----- | ------- (no connection)

NC  ----- | ------- (no connection)
Com \---- | ------- (white splice only-don't cut)
NO  ----- | ------- (ground)

Glossary
NO = Normally open
NC = Normally closed

good luck!