It's a good DIY project, mostly wrench work, but with some easy soldering if
you want to hook up the "city lights."   In addition to the headlight units,
you'll need to get the 6 hole electrical connector to replace the North
American 4 hole units.   006 545 80 28  for the socket and 009 545 30 28
for the socket cover, you'll need a pair.  To add the pin for the "city
lights" get a couple of  003 545 26 26 pins to solder jumper wires to and a
couple of snap type wire splices.

I'm assuming that you know how to remove corner lens and the headlight
unit.  After unpluggin the 4 pin connector, open it up with a small
screwdrive and write down the pin and wire color positions.  There are small
numbers molded onto the connector 1-4.  Transfer the wired pins to the new
connector as follows:  Put old pin 2 (brown wire) into socket 2, put old pin
1 (green wire) into new socket 6, put old pin 3 (yellow wire) into socket 5,
put old pin 4 (white wire) into socket 4.  The "city light" is connected to
new connector position 3 by soldering a jumper wire to the pin, then
sticking it into position 3.  If you splice the wire into the switched "hot"
wire of the corner light, the "City Light" will come on with the corners, or
you can wire it to an ignition switched  "hot" to have non-stop daytime
running lights when the car is switched on.

Very easy... just rearrange the wires in new 6 holes socket.