EntityLivingEquipmentChangeEvent is fired when the Equipment of a Entity changes. This also includes entities joining the World, as well as being cloned.

slot contains the affected EntityEquipmentSlot. item contains the ItemStack that is equipped now. olditem contains the ItemStack that was equipped previously.

You will need to cast the event in the function header as this class:
crafttweaker.event.EntityLivingEquipmentChangeEvent
You can, of course, also import the class before and use that name then.

EntityLivingEquipmentChangeEvent implements the following interfaces and are able to call all of their methods/getters/setters as well:

• ILivingEvent

The following information can be retrieved from the event:

ZenGetter	Return Type
ZenGetter newItem	Return Type IItemStack
ZenGetter oldItem	Return Type IItemStack
ZenGetter slot	Return Type IEntityEquipmentSlot