Is there any particular reason why you want to use DOS environment variables? Is it so that you can pass values between programs, or to provide some way to have persistent data? (DOS environment variables go away once the particular instance of COMMAND.COM or CMD.EXE exits)
If it's something to do with keeping a settings file you can easily edit in NOTEPAD or any text editor, you could just have a text file for storing these values. For example the contents might look like:

FEE=value
FIE=another value
FOE=yet another
FUM=still yet another value

You then just need to write a two functions -- one to read the contents, and another to update the contents.