Sure. It was documented in the Windows 98 Resource Kit that was on some CDs. There is also the MSDN web site which 98 articles are getting tougher to find.
http://www.google.com/search?hl=en&lr=&ie=UTF-8&q=UNATTENDED+INSTALL+WINDOWS+98+-XP+-2000 finds the usual and the noted bug.
Is there any program out there that one can use to easily set up an unattended Windows 98SE installation? I mean where I don't have to enter a product key or make selections. I want to start the installaion, walk away, and have a desktop when I come back. Is this possible?