[kornaut]

Все-таки вот, наверное, конечное решение проблемы, выданное самим Microsoft в статье http://support.microsoft.com/kb/234536

• When you are prompted by the Setup program, press F6 to manually install the mass storage drivers that you want.
• Perform a network installation of Windows. Network installations of Windows support unattended installations of mass storage drivers. For additional information about how to create an unattended installation of mass storage drivers, click the following article numbers to view the articles in the Microsoft Knowledge Base:
816299 How to create an unattended installation of third-party mass storage drivers in Windows Server 2003
288344 How to create an unattended installation of third-party mass storage drivers in Windows NT and Windows 2000

Note
Editing the Txtsetup.sif file to add mass storage drivers is not supported.

Мне тут явно подсказали в замечании, что нужно редактировать txtsetup.sif.