Yes, that will probably work, although an adaptor going that way might be rare as the dual protocol mice tend to go the other way.
The issue is that some mice were made to support both protocols - USB and PS/2. This type of mouse, when it powers up first, detects what type of connection it has and then switches to that protocol. It seems that many mice nowadays have dropped that feature and so won't work with that adaptor, even if they appear to be the same model as one which used to work. It's likely that a simple firmware revision in the mouse itself has removed the feature...
Edit: Yes, the Micromys is basically the same thing with a different connector. They both only support the PS/2 protocol.
