Someone correct me if I am wrong:
but BC model files are one-way deal. (only exporter, no importer. at least this was the explanation back at the beginning of the BC modding.) so in order to convert something you need the original 3d mesh in 3ds or milkshape or lightwave/lwo format.
The hard part is getting the BC models in those formats. (which you might want to ask the BC modding community.)