Using Custom Items for Custom Recipes?

How do I make recipes only makeable by custom items? Such as if I had:

Code:java

ItemStack chain = new ItemStack(Material.IRON_FENCE);
ItemMeta chainmeta = chain.getItemMeta();
chainmeta.setDisplayName(ChatColor.GRAY + "Chain Link");
List<String> chainlore = new ArrayList<String>();
chainlore.add(ChatColor.ITALIC + "Used for Chainmail.");
chainmeta.setLore(chainlore);
chain.setItemMeta(chainmeta);

Then I tried to make chain legs with it, such as:

Code:java

ShapedRecipe chainleg = new ShapedRecipe (new ItemStack(Material.CHAINMAIL_LEGGINGS, 1));
chainleg.shape("LLL","L L","L L");
chainleg.setIngredient('L', new MaterialData(Material.IRON_FENCE, chain.getData().getData()));

Now, with this code, I can make chain legs with both the "Chain Link" as-well as normal Iron Fence, I'm wondering how to make it to where its only craftable by "Chain Links."

Bump with reformat and new question.

EDIT by Moderator: merged posts, please use the edit button instead of double posting.