Actually, how to add the XP param to the Metadata Smelting? (MCP 7.18_pre1 & forge 6.0.0.328) 
  
I got it working: Just added this to the item (you could switch xp based on damage value then), just doesnt drop xp orbs: 
 
@Override
public void onCreated(ItemStack par1ItemStack, World par2World, EntityPlayer par3EntityPlayer) {
        int var2 = par1ItemStack.stackSize;
        float var3 = 5; //Exp for 1 Item
        int var4 = 0; //contains calculated xp to process
        if (var3 == 0.0F) {
            var2 = 0;
        }
        else if (var3 < 1.0F){
            var4 = MathHelper.floor_float((float)var2 * var3);
            if (var4 < MathHelper.ceiling_float_int((float)var2 * var3) && (float)Math.random() < (float)var2 * var3 - (float)var4) {
                ++var4;
            }
            var2 = var4;
        }
        else
        	var4=(int) (var2*var3);
        
        par3EntityPlayer.addExperience(var4);
}