Nevermind, found it!
Code:
--- Uses item in the container on another item in a container.
-- Uses an item in a specific spot in the container on a specific spot in a specific container.
-- @Class Container
-- @param spotfrom the specific slot the item to be used is at
-- @param contto the container index you want to use the item in
-- @param spotto the specific slot you want to use the item with in the new container
-- @return boolean true or false
function Container:UseItemWithContainerItem(spotfrom, contto, spotto)
self = type(self) == 'table' and self or Container.New(self)
return containerUseWithContainer(self._index, spotfrom, contto, spotto)
end