This page relates to Create, which does not have built-in support, you will need to install CreateTweaker as well!
Link to create-milling
The Milling mechanic is a type of IRecipeManager and implements all the methods that are available to IRecipeManager's, such as
Link to methods
Link to add-recipe
The following script will add a recipe that will output a Diamond and an Apple 45% of the time when a piece of Dirt is Milled with a duration of 100.
// <recipetype:create:milling>.addRecipe(String name, MCWeightedItemStack output, IIngredient input, @Optional(100) int duration) <recipetype:create:milling>.addRecipe("milling_test", [<item:minecraft:diamond>, <item:minecraft:apple> % 45], <item:minecraft:dirt>);
Link to remove-recipes
The following script will remove all Milling recipes that output Limesand.
// <recipetype:create:milling>.removeRecipe(IItemStack output) <recipetype:create:milling>.removeRecipe(<item:create:limesand>);