I have not ventured into actually modding units, but have the tools and they seem to be working... I used:
Python 2.6.6
PyFFI 2.19
Blender 2.49a
Blender NIF Scripts 2.5.07
Had some issues getting the NIF Scripts to install in the proper folder... I had some redundant folders, but maybe because of trial and error install/uninstall... anyway, I had a scripts file with subs under Belnder, and another under Blender/.blender. I ended up making copies of the modules and populating the folders so that each folder in the redundant copy had all the modules. The version of Blender I am using looks in the Blender/.blender/Scripts file.. I think. Still pretty new to all this...