User exit to derive Profit Center using MARA table for Inventory Manual pos

Hi

I have a typical scenario, where in currently users are posting materila code in FB01 transaction for some of the inventory balance sheet accounts (other than Cost of sales). As you are aware profit center is not derived directly from material code for general balance sheet items. I am trying to look out for an user exits which can be used in material substitution for deriving Profit Center. i.e.

When ever i enter a balance sheet manual posting inventory account, i am putting the material code, and i am trying to derive a profit center for the material using substitution rule. The system should look out for the material number using the user exit and update the profit center as per the material using Plant and material combination.

I know for PCA i can derive default profit center using 3keh or OKb9 for cost elements, but that will not solve the purpose.

Hence if any one of u know about the user exit which can help in deriving a profit center for material using MARA table, pls let me know

regards

Mahesh