How is it possible to enable porject info fields in Purchasin module, when using an Inventory item r

Hi, The problem we have to solve is the following:

We are currently implementing Project Costing, Inventory, Account Payables (update) and General Ledger (update)  and Purchasing modules. Client wants to monitor the commitment of the purchases that use the ITEM Inventory, the standard functionality of Projects does not allow to do so, you can only codify project info in Purchasing if the iTEM is expense, tha other way around, the fields of project information become disabled. Client wants  to monitor project info that comes from Inventory module, is that when you make the inventory release, you codify if and Project Costing register the real cost, becasue it appears a window where project info