Actually, now it looks like System doesn't have
enough privileges:
prnmngr -a -p printer1 -m "Kyocera FS-9530DN KX" -r port1
Microsoft (R) Windows Script Host Version 5.8
Copyright (C) Microsoft Corporation. All rights reserved.
Unable to add printer printer1 Error 0x80041003 Access denied
Operation PutInstance
Provider Win32 Provider
Description Access is denied.
Win32 error code 5
This works fine with a user in the administrators group.
EDIT:
Nevermind. The prnmngr command works as System in Session 0 (through Altiris in the hidden window), just not in Session 1 (the regular user window). The PrintUIEntry way to install an
unsigned printer driver works as System in Session 1, but errors out in Session 0.