I suppose you could get a seatpost binder bolt cable hanger and run a cable from the stop on your frame to the hanger. The bend would be tight, however, and add friction to the system. But I have a similar setup on a bike and haven't encountered trouble with it (not many miles on it, however).
Going with the v-brakes and levers might be more simple, and many prefer the ease of v-brake setup over cantis.