HOw to set the job cost master header account to PEC=N?

The documentation for setting up a job cost master reads:

"The system creates a general ledger header account for the job in the Account Master table (F0901).  This header account consists of the business unit, a blank object and blank subsidiary (or said another way, business unit, blank cost type and blank cost code).  Header accounts (also referred to as Job GL Accounts) enable the adjustment of the percentage of completion for a specific job when profits are recognized."

I have found that the header account is added to F0901, but the PEC should be "N". It is not. Therefore, users can post to this account. How can the job cost master header account be created with PEC set to "N" without having to do so through P0901. We are trying to restrict the users from modifying P0901, while at the same time allowing access to setup Job Cost Masters.