When I set up my update server a few weeks ago, I got the latest list from the Server Admin window, selected the updates that I wanted to have and wanted to share, made sure that port 8080 was open on my firewall and started the service. It took a while for the updates to all download from Apple.
On A client, in Terminal, I ran:
softwareupdate -l
to make sure they were up to date enough to use the limited updates that I have on my update server. I then ran (I work as root):
defaults write /Library/Preferences/com.apple.SoftwareUpdate CatalogURL
http://myserver:8088/
and veryfied /Library/Preferences/com.apple.SoftwareUpdate with:
plutil -convert xml1 /Library/Preferences/com.apple.SoftwareUpdate
cat /Library/Preferences/com.apple.SoftwareUpdate
then ran:
softwareupdate -l
again. This time it will report that it's contacting the new update server:
softwareupdate -l
Software Update Tool
Copyright 2002-2005 Apple
2007-09-26 18:48:13.261 softwareupdate[13714] Loading CatalogURL
http://myserver:8088/index.sucatalog
No new software available.
Roger