1. Start by creating an (empty) Bump Value layer.
2. Right mouse click on the Bump Value layer name and choose “Import Layer”.
3. Load the normal map file.
Note: In my example, I’m using a mesh that has multi UV tiles. In this case you need to choose only ONE file and Mudbox will recognize the rest.
At the first glance the display of the normal doesn’t look accurate. As a matter of fact, the normal map is displayed as a bump map.