Kit,
is is an easy doing... I have that done in my rebuild thread, too
http://www.7173mustangs.com/thread-tim-s-1973-mach-1-rebuild-thread
First, you have to separate the two bowed grey pin-plugs near the fuse panel without broking any latch (as I have done... :dodgy
Second, if you have a new connector plug with your set I would strip the black wire protection tube a bit and cut the old wires near the steering wheel, so that you have the old plug and enough of the old wire length and could see in which pin hole every wire goes.
Third, you have to loosen the 3 screws in your old steering columns switch assembly and get it out of it.
Fourth, you could remove the old black wire protection tube with the cutted wires and the old pin connector.
Fifth, you now could install the new switch assembly in your steering column before attaching the new connector plug. So you must fiddle the wires through the steering column till the fuse panel - don't forget the old black wire protection tube. But before tighten the screws in it I would look out for the routing of every old wire from the switch and compare it to the new switch assembly so you know which one of the new wires goes to which pin hole in your new connector plug. That's because the colors of the wires are a bit different. It's an easy way to find out the routing of the wires - just look carefully on your old switch, look out for the same wire color of the cutted pin connector and then for the right pin hole. Now you have to look for the same wire with perhaps a different color and connect it the same way. One after one...
Sixth, if you finished with that, "close" the new connector plug with the bar so they could not be loose anymore. Now you could put the two plug connectors together and try out
That's what I have done and it functions perfect since then - it is some of the easier and readily more satisfying operations...
Tim