Buy an aftermarket central locking kit from ebay (quite cheap) and install the motor into the drivers door and wire everything up as instructions and bobs your uncle.
This worked a treat in my Kia Sedona but it isn't an alarm, it will only lock the doors via the central locking through the remote. It is a very easy preceedure to perform if you are comfortable in working on automotive electronics.
NOTE: This will only work if the the locking rods inside the door are rods and not wire.
The other way is to fit the later 5AS alarm box ( it replaces the type fitted to yours which is obsolete) using either an adapter loom or getting the wiring connectors from a scrapper & joining them on. I just so happen to have a big box of brand new 5AS units........