That would be a bit of a challenge. You'd have to add caliper mounts to the fork (doable, but likely to cost you some unless you're able to DIY. if nothing else it'll mess up the paintjob). Setting up a disc brake for rod actuation would be another hurdle. And while I'm reasonably certain that you can find a disc brake hub to lace your current rim to I'm equally certain that buying a whole new disc brake wheel would be cheaper.

On a side note, getting rid of rod actuated brakes is often seen as a milestone in the early evolution of cars. Not that a bike it entirely comparable, but still.