B&A code

Assets =
{
    Asset("ATLAS", "images/newslots.xml"),
}

function backpackpostinit(inst)
    inst.components.equippable.equipslot = GLOBAL.EQUIPSLOTS.BACK
end

function amuletpostinit(inst)
    inst.components.equippable.equipslot = GLOBAL.EQUIPSLOTS.NECK
end

function inventorypostinit(component,inst)
    inst.components.inventory.numequipslots = 5
end

AddPrefabPostInit("amulet", amuletpostinit)
AddPrefabPostInit("blueamulet", amuletpostinit)
AddPrefabPostInit("purpleamulet", amuletpostinit)
AddPrefabPostInit("orangeamulet", amuletpostinit)
AddPrefabPostInit("greenamulet", amuletpostinit)
AddPrefabPostInit("yellowamulet", amuletpostinit)
AddComponentPostInit("inventory", inventorypostinit)
AddPrefabPostInit("backpack", backpackpostinit)
AddPrefabPostInit("krampus_sack", backpackpostinit)
AddPrefabPostInit("piggyback", backpackpostinit)
AddPrefabPostInit("icepack", backpackpostinit)

table.insert(GLOBAL.EQUIPSLOTS, "BACK")
GLOBAL.EQUIPSLOTS.BACK = "back"
table.insert(GLOBAL.EQUIPSLOTS, "NECK")
GLOBAL.EQUIPSLOTS.NECK = "neck"

AddClassPostConstruct("screens/playerhud", function(self)
    local oldfn = self.SetMainCharacter
    function self:SetMainCharacter(maincharacter)
        oldfn(self, maincharacter)
        self.controls.inv:AddEquipSlot(GLOBAL.EQUIPSLOTS.BACK, "images/newslots.xml", "back.tex")
        self.controls.inv:AddEquipSlot(GLOBAL.EQUIPSLOTS.NECK, "images/newslots.xml", "neck.tex")
        self.controls.inv.bg:SetScale(1.25,1,1.25)
    local bp = maincharacter.components.inventory:GetEquippedItem(GLOBAL.EQUIPSLOTS.BACK)
    if bp and bp.components.container then
        bp.components.container:Close()
        bp.components.container:Open(maincharacter)
        end
    end
end)