How do you change the material variance account used for a WIP Issue against a discrete job?

Upon WIP issue , we are trying to charge a different material variance account than what is specified in the job's accounting class. Is this possible to do? The WIP Issues form doesn't seem to have a place to change the account that is charged. We are also looking at doing this through the interface tables, but entering an account in the material_expense_account does not seem to do anything as it is still defaulting to the material variance account listed on the job's accounting class.