Walking horses (or at least most that I know, includeing Sunny) are GREAT at weaving poles. Sunny LOVES to turn fast! And Magic, anther Walker I know, is extremely good at them.
So breed-wise, you're probably set!
Like Iridehorses said, working slowly and working your way up is the best way to train them to it. Although that can be a bit challenging on a gaited horses as they have so many "slow gaits" and "fast gaits" and "in-between gaits", try to stay as close as you can to a flat walk, and then to a rack, and then eventually to a canter. Don't let him drift around through gaits. Keep him collected and in your hand, but give a bit when you turn the corners. Give him your leg if he drifts slower.
And when you say "trot" you do mean gait, right? By your username I automatically thought "gaited horse", lol
