One of the travelers of a 3 way was tapped for power to a receptacle

[Little Bill]

I found this on amazon, will this work. They had a lot of options!

If the power comes in at the rear door, then all you need is the Caseta, Pico remote, wall bracket kit.
If this is a multi-gang switch box, then he would need to get a wall plate that matches the switch type.
Example: toggle-Decora
or if more than two
toggle-toggle-Decora