It's nice to be able to unlock and lock your doors with a key fob rather than with the key.  Although I've never seen a Rabbit with power locks (other than Cabriolets), simple central locking is of limited value since it's easy in a car so small to just reach across and lock/unock the other door.  The real value is being able to have a remote function, where you can lock and unlock your car from a distance, and get visual feedback that the system has done its job.  

Most basic systems come in two parts - (1) the central locking system with controller and actuators for the doors, and (2) the remote sensor that picks up the signal from the key fob and activates the cental locking system.  Most will also integrate with a car alarm system, and have additional outputs so  you can do things like activate actuators to pop the rear hatch,

Installing these components is time consuming, but fairly straightforward.  Mechanically, the only thing to do is install the actuators.  The kit will come with brackets to support the actuators, and metal rods that clamp onto the existing door lock mechanisms.  All you have to do is remove the door panels and bolt everything in.  Here is a shot of how I mounted my lock actuators.  I had to drill a couple of holes in the doors to mount the brackets. Wiring is also relatively simple, all you need to do is follow the directions that come with the kit.  I've attached the wiring diagrams from the Autoloc kit that I bought, which should be very similar to any other kit you can find.  One item that may be specific to the Autoloc kit and is not clear, the yellow wire from the control box should be attached to switched power.  This enables the learning function of the unit so you can program the fobs into the system.  Be certain to adequately protect any wires that pass from the doors into the car, as otherwise these wires could be worn in half by the sharp edges of the door jamb.

To get the parking lights to flash, you have to install a common relay that will put power to the lights.  There is an 18 gauge gray wire from the light switch that I've noted on the wiring diagram linked below.

Click HERE to see the wiring diagram for the central locking system

Click HERE to see the wiring diagram for the remote control

Clikc HERE to see where to connect the parking light relay

Autoloc makes a good kit that has functioned flawlessly for me for a couple of years.  Parts Express also sells similar kits at a substantial discount, but I have no experience with this particular kit, although I've had great luck ordering from Parts Express in the past.