I wish I could post a photo, but no working camera. Still, it's not hard.
I made a small "tab" out of aluminum. crimped it into the tab that's already there.
A de-railer cable runs through a small hole drilled into my homemade tab. Small bolts and nuts above and below to hold this cable tight.
Above this assembly, mounted on the seat tube, is an L-bracket. teeny tiny hole in it. Cable passes through. Spring around cable from L-bracket to aluminum tab.
Above the L-bracket the cable runs (in a standard, black cable sheath) up to a thumb shifter mounted on the handlebars. Works like a charm.
Whether or not you need to put the effort (it's not much, though) into it depends on your climate. Those lucky folks in the golden state don't need this. But if you plan on riding when it's down close to freezing and below, then you do want to have a responsive, easy choke adjustment.