To set up TEMU's JIT virtual inventory, you need to follow the steps below:

1. First, open the TEMU virtual inventory management system and log in to the administrator account.

2. On the main interface of the system, find and click "Inventory Management" or a similar option.

3. On the Inventory Management page, find and select "Virtual Inventory" or a similar option.

4. On the Virtual Inventory page, you can see the current virtual inventory list.

5. To add a new JIT virtual inventory, click "Add" or a similar button.

6. On the page for adding a virtual inventory, fill in the relevant information, such as name, description, inventory quantity, etc.

7. Click "Save" or a similar button to save the changes.

8. If you need to edit or delete an existing JIT virtual inventory, you can find the corresponding item in the virtual inventory list and perform the corresponding operation.

Please note that different temu versions and configurations may vary. The above steps are for reference only, and the specific operations may vary. It is recommended that you consult the relevant documentation of temu or contact the developer or support team of the temu system for more accurate and detailed guidance.