The knees are use to move the pedals from left to right for one knee and vice-versa for the other. Yes, you do play it sitting. It is electric.Spaw is on target when he says it is very popular in honky-tonks. It is great for crying-in-your-beer, tear-jerker songs.
Basically, I hate the sound. But, occassionally, I hear someone use it grandly.
What's brown and looks good on a pedal-steel player?
A Doberman.
khandu