He gave me some instruction.
He said to use this link: http://users.skynet.be/FCB/files/DHModtool4c.exe
And to update to .net Framework 2.0 to make things work.
Everything's working fantastic, far as I can tell. I played and beat Indigo Prophecy (Fahrenheit, for those of you not in North America), and it was a fantastic game. The writing got a bit screwy near the end, but that's because it was apparently episodic then got switched.