Personally, I'd cut the suckers down at ground level and apply glyphosate or triclopyr to the freshly exposed phloem. I don't know why anyone would want to grow this awful pest plant.

To grow a tree from a stump sprout, just remove the sprouts you don't want to keep and let the one, or ones, you want to keep grow normally. The resulting tree may be more prone to failure, later on, as the stump rots away. Sprouts from the roots, as opposed to suckers from the trunk, would probably be the best choice.

The most vigorous part of the tree is the root to shoot transition zone. Since plant parts retain their ontogenetic age, basal sprouts are always very juvenile and have lots of vigor. You should be able to prune off basal sprouts with a VERY sharp tool & just stick them 6" into the ground in the spring before the push. If you keep them moist, they'll grow.

Al