Hello,
While some kinds of command line parameter are supported under [Associations] section such as: FileTypeCommandLine, FileTypeCommandLine-extension, ProtocolCommandLine, SendToCommandLine, ShellCommandLine; the command line switch/parameter for launching the app is poorly supported. It is only supported via myAppPortable.ini which is not so obvious and only support for main App.
My suggestion is something as below:
appinfo.ini
[Control]
Start=AppNamePortable.exe
Start1=AppNamePortable.exe
Name1=AppName Portable Mode1
StartCommandLine=/switch=mode1
Start2=AppNamePortable.exe
Name2=AppName Portable Mode2
StartCommandLine=/switch=mode2