@martius - my thoughts

A very simple way to see what command line options client Windows Update Agent (wuauclt.exe) has is to drop the executable in notepad. In the beginning of  the notepad (Word wrap enabled) you will find them!

In Windows 7 these options are available:

/DetectNow
/ReportNow
/RunHandlerComServer
/RunStoreAsComServer
/ShowSettingsDialog
/ResetAuthorization
/ResetEulas
/ShowWU
/ShowWindowsUpdate
/CloseWindowsUpdate
/SelfUpdateManaged
/SelfUpdateUnmanaged
/UpdateNow
/ShowWUAutoScan
/ShowFeaturedUpdates
/ShowOptions
/ShowFeaturedOptInDialog
/DemoUI 

Many of them are undocumented. What some of them mean can be found on the interwebs, others I have no clue!