Before you do anything, check the pump sprocket (plastic bit in the pump that normally shreds its teeth).

Chances are that will be worn and will end up leaving you in trouble with the roof stuck up, down or somewhere in between.

Get a metal version, I think the Escort Cabriolet Club have a source who makes them) before you do anything with it near the car.

As for fitting it, it is a case or removing the roof rams (you use the pump ones in their place), fitting the unit, making a holder for the relay in the boot area near the pump, run the wiring down the car, connect the supply to the ignition circuit so that it only goes live when the ignition is turned off.

Oh, and make sure you have the later nearside panel cover as they are different for the manual and electric ones.