It is possible to retrofit the "comfort windows" but it is a lot of work and you will need many parts.
Focus MK2/MK2.5 models with 2 electric windows are equipped with a conventional power window system. The windows are controlled directly by the window switch. Only the driver door has the quick down function wich is controlled by an extra electrical circuit in the driver door switch.
Focus MK2/MK2.5 models with 4 electric windows (and also some ST and RS models) are equipped with "comfort windows". The window switches gives just a signal by the CAN-bus network to the door modules which control the window motors (and some other functions). Door modules are only present in cars which have options that require the door modules. Benefits of this system are the quick up and down functions of all windows and the global opening and closing by the remote control.
If you want to retrofit the "comfort windows" you will need the following parts.
* The wiring looms in all doors.
* The window switches in all doors.
* Power window motor with door module for both front power windows.
* Complete mechanism with power window motor and door module for both rear windows.
Afterwards the door modules must be programmed to the car. I am planning to do this upgrade later this year and collected almost all the needed parts.