So what I've been using to back up the Registry (& various other config files) is the `Emergency Recovery Utility' (eru), located in Other|Misc on the Win95 disk. When you run eru, it prompts for a directory to save the backup to, suggesting a:. Ignore this suggestion and instead specify a directory on a zip or HDD, because eru does have the unpleasant habit of not telling you when it runs out of space to write its backups (anyway I find the 3 1/4 floppy to be a shockingly unreliable medium for the storage of information). Restoration can then be done by running the .exe that eru creates in the folder you specified, and this can be done in DOS mode.
Like I said, this is one way to do it, there's also a Microsoft Configuration Back-up utility, and a free program called lifesaver people use and speak highly of. More different methods are described in the Win95 books you used to be able to buy in the shopping Maul before Win98 came out; these strike me as being especially easy.