I did this with Wise Package studio in a similar way to the package for the installer service upgrade, except using the binary table:
1) Create a new MSI project
2) Using MSI Script and select the tab called "Execute Deferred"
3) Before the installfinalize section, add the command to "Execute Program From Installation"
4) Select the Windows SP2 Upgrade .exe file (to be executed from binary table)
5) Enter extra command line arguments - /quiet and /norestart
6) From the Properties tab and select:
Inscript options: Deferred execution - system context
Processing: Synchronous, ignore exit code