How to add record in Inventory Journals manually?

Hi,

I want to create functionality which perform inward and outward transaction of stock. I have review the flow and got to know that Inventory Journals keep record of Inward and Outward track of Inventory for particular product and warehouse.

I have tried to add record using AJAX call in webresource. But as it says that it is not possible to add record manually in Inventory Journals.

I want to perform 2 transaction. 1- Inward, 2- Outward(negative value)

Can anybody suggest me how to manage this?