Add two switches to the Devo 7e

yes the diode is needed regardless.
I made a previous statement that they aren't but I was wrong.

Jman841 wrote: ok thank you! Guess I will be learning how to solder diodes today.

Just out of curiosity, what is it needed? Isn't the switch just completing a circuit?

In the switch mod what you are doing is making adding a switch that looks like a button. To save wiring, the buttons are actually wired together in a grid (much like your keyboard) to allow a few wires to detect many more buttons. The downside of this, is that there are many cases where holding multiple buttons simultaneously can't be detected. Since we're treating a switch like a button, it is as if we are holding it down forever. This would prevent other buttons from being detected if the diode wasn't there.
The diode only allows current to flow in one direction. This allows us to read the buttons in one direction and the switches in the opposite direction. Basically it means activating a switch doesn't affect our ability to read the buttons.

Yes you can follow those instructions. Note that if you ever want a 2nd switch you will need to rewire the 1st one since the "two 3-way switch" mod is different than the "one 3-way switch" mod. These days the best option is to use a nightly build. Then you do not need to patch the firmware at all, and can instead just edit the hardware.ini file.