The water flow should be fine in the breeder box. You'd be better off with a solid container. an airstone, and some methylene blue. If the current breeder box has slits in the bottom...your other fish will suck the eggs out. The advantage of the solid container is: you can treat the water inside it, without treating the whole tank. Float it in the main tank, to maintain proper temperature. In 3-4 days (depending on temp) you should have wigglers. I another 3-4 days...they should be free-swimming, and ready to eat! After that...it's all feeding and proper filtration
Best of luck!