system
A chat on subreddit /r/pcmasterrace
human
But you also needed to make a backup first so that it is easy to undo the changes 20minutes later when you need the other program to run.
gpt
I set up an MSDOS boot menu that had custom autoexec.bat and config.sys for certain games. As part of the standard boot, it would execute a stripped-down autoexec.bat and then execute the remainder with the batch script (trimmed down to that particular program need) from the menu, it would then replace the default config.sys with the custom config.sys for the game/application, then reboot to load it. It worked great, used it for many years.