Adding variable intermittent wipers on an early box, the easy way

[ray_pilot]

I may be coming late to this thread, but I need a better explanation. Obviously I can get that VW relay and swap out the existing one. I understand that. But where does that knob (on the left side of the radio) come into play. i just have a blank spot there. And I've never tried, so how can you put the wiper in 'intermittant mode" if that doesn't exist? Thanks.