I've replaced the same switch assembly on a couple of Fiesta's It's very easy, the cowl around the steering column is held in place with 4/5 screws, with this off you will see a single screw that holds the switch assembly in place, then you twist/rotate the assy towards you then unplug the connector.
If it would help I have the full write up with pictures from the Ford manual if you contact me on nige110162(at symbol)hotmail.co.uk I'll mail you the info
nigel
January 2012