|There's probably other ways but this should work. First do you have the full version 5.0 disks in case it doesn't?|
If yes then boot up with the first 6.22 disk and exit the installation. At the dos prompt type:
attrib -s -h -r c:\msdos.sys and enter. Then
attrib -s -h -r c:\io.sys and enter. Then
del c:\msdos.sys and enter. Then
del c:\io.sys and enter. Then
del c:\command.com and enter. Then
ren c:\config.sys config.old and enter. Then
ren c:\autoexec.bat autoexec.old and enter.
That deletes the dos 5 system files and renames your existing config.sys and autoexec.bat. I'm not sure if it's necessary but for good measure delete the dos directory:
del c:\dos\*.* and enter. Then
rd c:\dos and enter.
Then restart the 6.22 installation or reboot and let it start.
If you don't have the dos 5 disks then do the above at your own risk--but it should work. Or others may post in with other advice.