wiper switch question - installing intermittent wipers

[1978sierra]

I am wondering if anyone has a link for an intermittent wiper switch install. I'd like to do one in my 78. Currently, the switch only functions as off and high (in the middle position) and sprays when depressed. I'd like to switch to something like this :

http://www.rockauto.com/catalog/more...074&cc=1030341

Is it as simple as just changing the switch? will there be a bunch of wiring? do I need any other parts?

I've dug around with the search for the past hour but can't seem to find what I am looking for.

Any help would be greatly appreciated. As always, everyone here is awesome!

Cheers,