It takes patience and some persistence, trying each mode backwards (I got a friend's expensive old Acer slide scanner to work in 98 mode) and making sure the .exe file holds the mode, as Administrator if necessary
Sometimes, in games for example, you need to make both the installation .exe and the game player .exe in the same compatibility mode. Drivers
are the trickiest since not all drivers come in executable installers. How do others get drivers to run in another mode?