In a small saucepan, heat soya milk to very warm, but not hot (45°C if using a candy thermometer). Fit an electric mixer with a dough hook. Pour warm soya milk in the bowl of mixer and sprinkle yeast over. Mix to dissolve and let sit for 5 minutes.
With mixer running at low speed, add sugar, salt, margarine, cinnamon, nutmeg and "eggs". Gradually add flour, dough will be wet and sticky, and continue kneading with dough hook until smooth, about 5 minutes. Detach bowl, cover with plastic wrap and let the dough "rest" for 30-45 minutes.
Return bowl to mixer and knead until smooth and elastic, for about 3 more minutes. Add currants or raisins and knead until well mixed. At this point, dough will still be fairly wet and sticky. Shape dough in a ball, place in a greased dish, cover with plastic wrap and let rise overnight in the refrigerator. Excess moisture will be absorbed by the morning.
Let dough sit at room temperature for about a half-hour. Line a large baking pan (or pans) with parchment paper (you could also lightly grease a baking pan, but parchment works better). Divide dough into 24 equal pieces (in half, half again, etc., etc.). Shape each portion into a ball and place on baking sheet, about 1/2 inch apart. Cover with a clean kitchen towel and let rise in a warm, draft-free place until doubled in size, about 1 1/2 hours.
In the meantime, preheat oven to 200°C.
When buns have risen, take a sharp or serrated knife and carefully slash buns with a cross. Brush them with "egg" white and place in oven. Bake for 10 minutes, then reduce heat to 180° F, then bake until golden brown, about 15 minutes more. Transfer to a wire rack. Whisk together glaze ingredients, and spoon over buns in a cross pattern. Serve warm, if possible (Hot Cross Buns).