The 3rd parameter when creating an itemstack is always the metadata. See Below:
ModLoader.addShapelessRecipe(new ItemStack(TFCItems.SinglePlank, 3, 0), new Object[] {new ItemStack(TFCItems.Logs, 1, -1)});
In the Above example notice the logs itemstack has a -1. This means that the recipe can use a log of any metadata at all. Then look at the SinglePlank itemstack, the 0 says that the result will be SinglePlank:0. I probably overexplained, but there you go. I hope that helps.