Combine first 3 ingredients in a bowl. Stir in 3/4 cup boiling water. Let stand for 15 minutes.
Dissolve 1 tablespoon sugar, molasses, and yeast in 1/4 cup warm water in a large bowl; let stand 5 minutes. Stir in cornmeal mixture, remaining 3 tablespoons sugar, butter, and salt.
Lightly spoon flours into dry measuring cups; level with a knife. Add 1 3/4 cups all-purpose flour, whole wheat flour, and rye flour to the yeast mixture; stir until a soft dough forms. Turn dough out onto a lightly floured surface. Knead until smooth and elastic (about 8 minutes); add enough of the remaining all-purpose flour, 1 tablespoon at a time, to prevent dough from sticking to hands (dough will feel tacky).
Place dough in a large bowl coated with cooking spray, turning to coat top. Cover and let rise in a warm place (85°), free from drafts, 1 1/2 hours or until doubled in size. (Gently press two fingers into dough. If indentation remains, dough has risen enough.)
Punch dough down; cover and let rest 5 minutes. Divide dough into 16 equal portions. Working with one portion at a time (cover remaining dough to prevent drying), roll dough into a ball. Place rolls 1 inch apart on a baking sheet coated with cooking spray. Cover and let rise in a warm place (85°), free from drafts, 45 minutes or until doubled in size.
Preheat oven to 400°.
Bake rolls at 400° for 15 minutes or until golden brown. Cool on wire racks.