Go to Uppervolta (in the "TEATIME,FULLTIMEうぷろだ" section).
Download the following file:
js2up0141 (ODFConvertor & ODFMeshExtractor).

If you can't access UpperVolta, you can download a torrent which I have created, which contains archives of all Touhou LD2 mods listed on this guide (except for Koishi Komeiji, whose archive is mysteriously no longer on any of my hard drives), plus the tools needed throughout this guide. You can download it from here. Info on it is here.
(Link and torrent fixed on 2014-11-15)

This archive contains files for editing ODF archives, which contain models and other stuff.
Do not get confused with js2up0041 (ODFConvertor1.11a), which is not the one you want.

→ Okay, I have the tools!