Combine 2 cups of the flour and the remaining dough ingredients in a large mixing bowl. Beat well with a wooden spoon for 2 minutes. Stir in as much flour by hand as you can. Turn in out onto a wooden board that is well covered with flour and knead in as much flour as needed to make a moderately soft dough. Knead for a few more minutes until smooth and elastic. Place in a greased bowl and cover with a towel. Let rise until double in size (an hour or so. It dosen't have to be exact).
Take the dough back to the wooden board and dump it out of the bowl. Roll it out into a rectangle about 8 inches wide by 18 inches long. For the filling, spread the 1/2 cup softened margarine over the dough (not the bottom inch, though) and then sprinkle the sugar and cinnamon on top of the margarine.
Starting from the top, roll it up, pinching it together at the bottom to seal the long roll (this is why you didn't put margarine on that part).
With a serrated knife, cut the long roll into 12 or 15 rolls (depending on how large you want them to be.) Place the rolls in a 9 by 13 pan that has been greased and lined with parchment paper (this will keep the bottoms from burning and the rolls from sticking.) If you have 12 rolls, there should be 3 across and 4 down. If you have 15 rolls, there should be 3 across and 5 down.
At this point, you can put the rolls into the fridge and take them out in the morning to bake fresh for breakfast. Take them out about 30 minutes before you want to bake them, and make sure that they are well risen before you bake them. OR, you can let them rise at room temperature for about an hour, and bake straightaway. Bake in an oven that has been preheated to 350 Fahrenheit for about 30 minutes (check at 25 minutes for doneness).
To make the icing, whisk the 2 tablespoons softened (not melted) margarine with some powdered sugar. Keep adding the powdered sugar until it feels stiff to mix, and then add a splash of soy milk to thin it out slightly. Let the rolls cool for a few minutes, ice, and enjoy.