You should be able to replace 7z.dll with alternative versions, provided that they have not changed the 7z API and have a suitable version number.
I do not know enough about this fork of 7z.dll to say if that is the case or if there would be other barriers to supporting it. At the moment we only intend to support the official 7z.dll releases, but we do not do anything to stop people swapping the DLL for alternative versions if they wish, as long as the DLL is compatible with the original's interface.
Note that you may need to fully exiting Opus (via File / Exit Directory Opus) after replacing the DLL for the new one to be picked up.