Currently I have an Installshield 2008 install and am working on switching over to Setupbuilder 7.3.

As part of the install, We are uninstalling the old version of the program. In order to do this completely, we have to run this command line:
Run Command Line "C:\Program Files\InstallShield Installation Information\{820020E9-082B-49AD-9467-EF5815C61D1A}\setup.exe" -runfromtemp -l0x0409 -removeonly [Wait]

I have it set to Wait, but it doesn't instead the Instalshield uninstaller seems to kick off another program and the setupbuilder install attempts to continue.
Is there a way to force setupbuilder to wait?
Or at least to make it not the foreground application?

I want the user to complete the uninstall of the previous program before they install the new one.