Yes, you shuold be able to do so.
While I'm no expert on the subject, what Group Policy does, is push a
configuration set out to your clients.
And this configuration is entirely registry based (at least the SUS part
is).
Here's a couple of pages describing how to do it:
http://support.microsoft.com/kb/328010
http://www.winguides.com/registry/display.php/1241/
http://web.mit.edu/ist/topics/windows/updates/explanation.html
// Henrik
> Can I Update clients without implementing Groip policy or
> without Active directory architecture using SUS Server.
> If yes , do i need to install any client on the
> workstations or do some modification s so that my
> workstation can communicate with SUS Server.