If you're using buttercream icing and want it to look like fondant, wait until the buttercream frosting gets a 'crust' on it, then just take a plain white paper towel (like Viva or Bounty), lay the inside that was closest to the roll on top of the cake, and smooth it with your hand or fondant smoother. Then do the same with the sides. Voila! Perfect, smooth icing on your wedding cake, ready to be decorated! Thank you Debbie for the info!