After downloading the plugin , simple copy the file smooth.hxt into the HXT directory your desired A:M installation . The plugin was originally designed as a working relief for me, and therefor raises far no claim to completeness or accuracy, however it is freeware .
Start the plugin with RMB->Plug-ins->Wizards->Correct Normals with a selected model. The model must be in the frontview (Numpad - 2) . If there are some patches found , where the normals are reversed , this patches are selected after the plugin is finished.