The only tools you need would be a small screwdriver to push a tab. Everything snaps together.
Here is a list of wiper switches you can use. It comes from Yarisworld apparently they do the same mod. The difference between the two is the newer switch has icons and the older has text. I have been looking at eBay and checking local scrap yards for a few weeks. The only one I have been able to find is from the older Prius. Mine was $50 including shipping.
I disconnected the negative cable from my battery first. It may be unnecessary, but anytime I play around the steering column I get paranoid about accidentally activating the air bag. Better safe than sorry.
Here is the part I received from eBay. It has both the wiper and headlight switch. It was actually cheaper than the auctions for just the wiper switch.
Just push this tab to separate the wiper switch from the assembly. It is easier to see here than in the clutter of the steering column.
Here it is apart.
To get to the switch on the steering column look for the seam where the top and bottom covers meet. Squeeze the bottom cover right below the seam. It should pop apart. You can then pull it off. The top will just pull off as well.
Here is what you should see.
Find these two white plugs on the bottom of the switch.
Here is the same tab to push as on my new part. Push it and the switch just slides out. (Ignore the dust
Here is a side-by-side of the xB and Prius switches. You can see the Prius switch has a few extra pins. I'm assuming they are for the dual-speed rear wiper. No wires go to them on our xB's. Apparently there is a relay at the rear wiper motor on the vehicles this switch comes from that is required for the two speeds. The guy at Yarisworld said it also requires a return wire from the relay to the switch. It might be interesting to try, but sounds like a pain. Also, I don't have a car to look at to match up wires.
Now just reverse the process.
Snap the Prius switch into place.
Plug in the two wire connectors.
Snap the steering column covers back on.
Reconnect the battery cable.
(Reprogram all of your radio presets.)
I think it actually took longer to reprogram my radio presets than to swap out the switch! The whole process was done in about 10 minutes.
If you're interested, here is the link to the diy at Yarisworld. It is similar, but they have a few screws to take out.
DIY - Liftback Intermittent Wipers via Stalk Replacement (v2.0) - Toyota Yaris Forums - Ultimate Yaris Enthusiast Site