You can use regedt32.exe from another instance of W2K and load the old hives into it.
In c:\winnt\system32\config is a copy of the live registry files, these hold all the data you require.
Select load hive from regedt32.exe and you can them import the old hives from the above location.
Edit what you want, resave the hive and you're off.
It's not DOS but if you have a second W2K, that would work. You could also stick that HD in another PC (as slave) and use the above method with regedt32.