Setting up and assigning Value set to Oracle delivered field

I would like to set up a value set and assign it to the "Demand Class" field in the Organizations Parameters - Inventory Parameters form. I would like to use this line that currently has no LOV assigned to it to enter business specific informationfrom a value set that could be utilized in reporting for the Organization. How do I set up and assign a new value set and link it to this open field in the form? See the attached form witht eh Demand Calss field I wish to populate.

Thanks

 Kim