Perhaps there is some undocumented process you can uncover.
Below are some command lines found to work,
try "setup.exe /?" first then go through the list below- you may get
lucky!
- setup.exe
/q
- setup.exe
/qn
- setup.exe
/silent
- setup.exe
/s
- setup.exe
/NoUserInput
- setup.exe
/unattended
- setup.exe
/CreateAnswerFile
- setup.exe
/quiet
- setup.exe /passive
- setup.exe /NoUI
- setup.exe -s
- setup.exe -silent
- setup.exe /VerySilent
- setup.exe -r (Creates response file in Windows directory with name setup.iss)