In any DOS installation, type "help", then look for "multi-config", there you have the instructions:
... And then read about the commands: "menuitem", etc.
You can also look for batch sctipting commands, etc. Enjoy.
The pictures above are from the help program included in DOS 6.22, not sure about previous versions, both regarding the help program, and the very possibility to set up multiple configurations.
Multiple configurations are only useful if some applications need a lot of conventional memory, while others need additional resident programs that use it up, or if some need an expanded memory manager while others are incompatible, etc.