Use CNS0 to create a Delivery Document. This delivery is a Delivery without reference to a material. It is used when you need the functionality of a Delivery Doc (Packing List, Shipment Notification, other paperwork, etc.). You do not do PGI with this document. COGS is whatever was posted to the WBS and settled. Revenue can post to the WBS from the Sales Order when you do billing.
Now you could do the negative component for a material and then post a consumption to the WBS. Here's what you're going to get:
1. The FG must be costed either manually or by CK11N. Probably can't use CK11N because you aren't using PP for this material. So you need to cost it manually and enter it on the mateiral master.
2. Post a Goods Issue of the negative quantity material. This will credit the WBS with the material cost and debit inventory.
3. Do a normal Delivery of the FG and PGI it from inventory. Nothing posts to the WBS here. You will get a credit to inventory for the value on the material master and a debit to the Sales Order.
4. Now, on the project, you are left with the variation between your actual costs posted to the project and whatever you entered on the FG material master. This delta will be settled whereever you put on the WBS settlement rule.
Standard Make to Order process is the fist process.