No, it's registry key you have to modify in order to disable the DLS auto-replacement, or remove GM.dls from the list of protected files.
The information that I'm basing this method on can be found
here.
Granted, its for WinME, but the other versions of windows probably do the same thing the same way.
1.) Open up C:\Windows\System\Restore\filelist.xml in notepad/wordpad.
2.) Search the file for any mention of GM.DLS, and remove it.
3.) Save the file.
Hopefully, that should make windows turn a blind eye to your manual replacement of GM.dls.