NewWolf port has a built-in support for replacement of 2D sprites with fan-made 3D models, which you can take from the project's page on SourceForge.net. This is a link to download page for models.
Installation instructions:
Download and unpack models' archive to the project's folder (in my case this was 'e:\games\wolf3d\'). Check that the contents of 'Basewgl\' folder merged correctly, so the list of files inside is as following:
If everything was unpacked correctly, the only file added should be 'pak2.pak' file.
Start the game using 'NewWolf.exe'. No further configuration is needed, as the game will find and use models resource files automatically.
This model pack has been compiled from different sources and projects. Unfortunately, this pack only replaces weapons and objects, so all enemy characters remain 2D.