Well, I took out a standard DVI cable and carefully opened up one end:
The pins on this single link DVI-D cable are not complete, and Apple used some of the non-existent pins on the ADC side of things. I had to move 3 pins (1, 9 and 17) to the area in the middle (4, 12 and 20). I drilled holes using a PCB drill and pulled out the pins with long nosed pliers. I then placed them (pins and all) on the ADC port of the video card and applied some epoxy to the area around the hole (the holes were too big).
This is after all 3 pins were moved.
I then carefully used a good combination of shrink tube on the wires so that nothing will short.
After testing this to verify that it works, I epoxied the black part back on to the shell. Now I have 2 screens hooked up to the Powermac G5.