I tried doing this several ways, but now I don't think it's possible. I'd be glad to stand corrected on this, but I tried everything I could think of, including adding NETWORK SERVICE to Administrators, tweaking all sorts of Local Security Policy settings, etc.
When I enable auditing, I get this:
Event Type: Failure Audit
Event Source: Security
Event Category: Account Logon
Event ID: 680
Date: 02/03/2010
Time: 8:49:53 PM
User: NT AUTHORITY\SYSTEM
Computer: RESULTANT
Description:
Logon attempt by: MICROSOFT_AUTHENTICATION_PACKAGE_V1_0
Logon account: NETWORK SERVICE
Source Workstation: RESULTANT
Error Code: 0xC0000064
Event Type: Failure Audit
Event Source: Security
Event Category: Logon/Logoff
Event ID: 529
Date: 02/03/2010
Time: 8:49:53 PM
User: NT AUTHORITY\SYSTEM
Computer: RESULTANT
Description:
Logon Failure:
Reason: Unknown user name or bad password
User Name: NETWORK SERVICE
Domain: NT AUTHORITY
Logon Type: 4
Logon Process: Advapi
Authentication Package: Negotiate
Workstation Name: RESULTANT
0xC0000064 decodes to NO_SUCH_USER. That's a bit silly, considering that I entered only network service – how did it know that the account that failed was in NT AUTHORITY?
When I enter an invalid username, I don't even see the authentication attempt at all. So clearly something agrees that NETWORK SERVICE is an actual account.
If I botch the password for a known username (ie Administrator), I get 0xC000006A (STATUS_WRONG_PASSWORD).
Try adding the Log on as a batch job right to NETWORK SERVICE. I think it's a silly idea; you should just bite the bullet and create a domain account…