CLI switches for wuapp.exe

Can anyone point me to a list of CLI switches for the Windows Vista/7 update program, and what those switches do? I've been Googling for one, but if it's on Microsoft's website, it's not very obvious.

I'm particularly interested in an equivalent of update.exe's /z switch, which allows updates to be installed without automatic reboots...

Edit: okay, there is clearly more to this than meets the eye.

a) wuapp.exe is the wrong program, it's the GUI frontend, like the update manager in XP. Where's the CLI frontend?

b) On a somewhat related note, update.exe is missing, yes, missing, from my very legitimate copy of Windows XP Home. Missing from the CD, missing after a fresh install, missing no matter where I look. Does it only ship with Pro or something? Can I get it from somewhere on MS' website?

Edit again: N/M I'm stupid. update.exe is the individual update installer. The program I want is qchain.exe. Now if only I could find where the heck that is.