First off... Use this as a GUIDE to an install... I will NOT be held responsible for 'idiot' moments in case something gets damaged due to YOUR doing.

At the request of a bunch of members, I'm making this DIY for the WebElectric One-Touch Turn Signals. They allow you to just 'tap' the signal stalk to signal either 1-8 times... A factory option on the higher priced 'luxury' cars. Also, this unit will allow you to use LED bulbs for any turn signals without causing 'hyperblink."

Product can be found here (I am in no way affiliated with this company, they just make useful products):
WebElectric Products - Sequential Turn Signals, Sequential Taillights, Sequential Tail Lights, Dynamite Stick Sequential, Pulsing Brake Light Pulser Flasher, One Touch Convertible Top, Dynamite Stick, One Touch Turn Signals, Daytime Running Lights, L

Once on the site, look on the left column and click "One-Touch Turn Signals" > scroll to find the one that has the picture of a Prius - "Toyota/Lexus OTTS > click buy now

Pics and short directions here:
Start here... by opening the driver's door

Use a pry tool or screwdriver to pop open the side panel, make sure NOT to scratch anything

Once you pop the cover off, you'll be facing the side of your dashboard... There are two Phillips screws to remove... locations are at the end of the screwdriver and pry tool.

Once you get that off, you'll have to use some firm persuasion to pop the knee panel off... Don't pull it out too far because you'll need to disconnect a couple harnesses....
**Side-note: if you have the OEM footwell accent lighting, you don't have to disconnect the power wire, but it may make it easier to do so so you can pull the knee panel out of the car.**

Next is the mildly tricky part; take two flat head screwdrivers or pry tools, and at the locations pointed, there are two clips you need to press so you can pull the relay box towards the REAR of the car. Again, don't pull too hard cause it's connected to a harness.

THIS is what you're looking for. The flasher relay located at the very TOP of the relay box.
**Note: I already had the OTTS installed before I was asked to make this DIY**

The stock relay looks like the one on the left

After disconnecting the harness from the back of the relay, stick a small flat head or pry tool between the top of the box and bottom of the relay, then slide it out of it's retainer.

The re-install is just reverse. Enjoy! Hope these were helpful...

Once everything is done and functioning.... Onto programming:
1) Start the car or turn the key to position 2 (on)
2) Tap the RIGHT TURN signal 5 times within 3 seconds. After 2 seconds the signal will flash once.
3) Hold the RIGHT TURN signal on for the number of flashes desired. Make sure you include the full last flash.
4) Release the signal lever. After 2 seconds, the signal will flash the new number. Programming is complete.

Here's the final product... (excuse the dash, I was still working on stuff)