The Bootcamp setup.exe is a silent Installer. See the following part from AutoUnattend.xml.
</settings>
<settings pass="specialize">
<component name="Microsoft-Windows-Deployment"processorArchitecture="amd64"publicKeyToken="31bf3856ad364e35"language="neutral"versionScope="nonSxS"xmlns:wcm="http://schemas.microsoft.com/WMIConfig/2002/State"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<RunSynchronous>
<RunSynchronousCommand wcm:action="add">
<Order>1</Order>
<Path>cmd /c "FOR %i IN (X F E D C) DO (FOR /F "tokens=6" %t in ('vol %i:') do (IF /I %t NEQ "" (IF EXIST %i:\BootCamp\BootCamp.xml Reg ADD "HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\Environment" /v AppsRoot /t REG_SZ /d %i /f )))"</Path>
</RunSynchronousCommand>
</RunSynchronous>
</component>
</settings>
<settings pass="oobeSystem">
<component name="Microsoft-Windows-Shell-Setup"processorArchitecture="amd64"publicKeyToken="31bf3856ad364e35"language="neutral"versionScope="nonSxS"xmlns:wcm="http://schemas.microsoft.com/WMIConfig/2002/State"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<FirstLogonCommands>
<SynchronousCommand wcm:action="add">
<Description>AMD CCC Setup</Description>
<CommandLine>%AppsRoot%:\BootCamp\Drivers\ATI\ATIGraphics\Bin64\ATISetup.exe -Install</CommandLine>
<Order>1</Order>
<RequiresUserInput>false</RequiresUserInput>
</SynchronousCommand>
<SynchronousCommand wcm:action="add">
<Description>BootCamp setup</Description>
<CommandLine>%AppsRoot%:\BootCamp\setup.exe</CommandLine>
<Order>2</Order>
<RequiresUserInput>false</RequiresUserInput>
</SynchronousCommand>
</FirstLogonCommands>
</component>
</settings>