I've created an import/export script for Blender (v2.65+) that can import and export VISION engine IFF 3D models. You can get it on GitHub here: https://github.com/Talon1024/WCPBlenderExporter
Most models from WC:SO mods are supported, as well as some models from the original game.
Installation guides and tutorials are available on GitHub.
I've released a new tool for you aspiring modders out there... It's a converter that reads OBJ files and writes WCPPascal source code, which can then be compiled into an IFF using WCPPascal. The program is written in Java and the source code is included in the download.
It's still a beta version, so it may not work for some models. If you have any problems, post a description of the problem and a screenshot if necessary.
The converter is currently limited to 4096 polygons and 4096 vertices.
You can get it here: http://www.ciinet.org/kevin/java/index.html