Internet archive seems down so I can't check the wayback machine, I feel silly asking here when I could be asking on a Descent related forum but I don't feel like registering anywhere just to ask one question.

The tool I remember using was part of a set of utilities under the name "Descent Manager", a group of utilities that could also deal with Volitions format used in Red Faction and Freespace 1&2.

EDIT: Internet Archive came back up, managed to find it finally.