Been playing around with an inf file to install dos AFTER win9x.
I get... bored.

I think I figured it out. Ie it worked once.

BIG CAVEAT! I assume this will only work on FAT partitions. NO FAT32.

Instructions:
Copy all into a folder. Add dos 6.22 files from floppies without overwriting.
In win9x rightclick the inf > install.
It should create a c:\dos folder, mod the msdos.sys, and copy the standard dos boot files.
Assuming it works on other machines, you will have installed dos after 9x which is... kinda cool.

THIS IS TEST QUALITY. IT SHOULD NOT BREAK ANYTHING BUT IF IT DOES, THAT'S ON YOU.