If you're talking about the electrical part of the switch, you have to remove 3 screws from the back of the keyed section, unplug the old switch, plug in the new switch and reinstall the switch onto the back of the keyed section.
It sounds easier than it is.
You need a mirror, light, stubby screw driver or the shortest scew driver you can imagine to remove and reinstall the 3 screws from the switched portion...not much room behind the switch....
It's really plug and play, just a very cramped work area.
The more you do, the easier it gets.....I've changed maybe 3 in my 40 years of driving a 240....so it still ain't that easy....yet.
Laying on your back, make sure you've got something soft to lay on.

If you're talking about changing the front part of the switch where the key is inserted.....can't help you.....good luck.

Hope this helps