If you are using the standalone version, just go to the shortcut properties, wrap the “target” path into quotation marks and add -2002mode argument (e.g. "C:\Program Files (x86)\Chicken Invaders Universe\CIU.exe" -2002mode). If you are using Steam, add -2002mode as a launch option in the game’s properties.
The music won’t be there but it can easily be modded back.