It isn't the easiest proposition.
You need to drop the rear of the subframe, remove all the mounting hardware, remove the sway bar, possibly the y-pipe, remove the linkages, etc. One of the most experienced guys on here (Spridget) actually took his to a shop to get it done rather than screw with it himself. Look around for the Ford Service CD downloads and take a look at that. It should answer all your questions about replacing a rack.
JR