You cannot hook up a standard dimmer. What happens is the linear 3 way becomes a non-load controlling switch. So, the 500w switch goes where the line comes in, controls the load, and the other switch is just connected to electric without load (like an outlet).
I have several of these in combo around the first floor. You can add as many 3 ways as you want, creating virtual 4 and 5 way switches. What you do is you program the 3 way as a controller of the other switch - I’m using the wrong terminology here, so hopefully someone can explain that part better. I needed an Aeon minimote to get them setup.