This is copied from the SE newsgroup. The original answer was posted by John Doyle. The detailed instructions that I have copied below are from PellaKen. PellaKen is also a member here at eng-tips.
From PellaKen's newsgroup post dated 3/12/2003.
To run SE updates silently, perform the following steps:
Open the SEUPDATE.EXE file in Winzip (or some other app that can decompress
installation packages) and extract the files to a folder using the USE
FOLDERS option (this would most likely be a network location so that all SE
PC's can see it).
From a Command Prompt, run SETUP -R. This will install the update on the
local PC just like normal, but it will also create a SETUP.ISS file which
will then be used for future installations in a silent mode.
Copy the SETUP.ISS file from the C:\WINDOWS directory (this is where it is
placed when it is created. Open it with Notepad and insure it is for SE) and
place it into the directory where you extracted the update to.
Silent SE updates
To install the update silently on other PC's, at a Command Prompt, type the
path to the extracted update with the following at the end: SETUP -S
Example: \\myserver\seupdate5\setup -s
You should now be installing the update silently.
Thanks, Ken. I hope you don't mind me posting this here. You should create a FAQ for this.
--Scott