As I mentioned previously there are really two ways of getting the cinema display signal through the neck. The first method was to remove the pins from the connectors when possible, remove all existing wires from the 20" neck and replace them with the cinema display cables. This method has the advantage of minimal soldering (especially of the very small cables), but getting the wires through is tedious. Although the wires are similar the shielding is thicker on the cinema display cables.
The second method is to use the existing wires in the iMac neck and solder them to the Cinema Display Connectors at each end. (With one notable exception). To start I removed all the protective tubbing from the cinema display cable. The cable is composed of 4 separate wires.
1) The Power Cable - 3 wires - including 24V
2) The DVI cable - This cable actually splits into two parts on the monitor side of the cable
A) TMDS Signal Wires - The equivalent of the black cable of the iMac - 4 triplet wires = 12 total
B) TMDS Power/Data/Clock - The equivalent of the gray cable. This contains the clock, data, hot plug, EDID, and ground. There are less cables than the grey cable because the power (VCC and ground cables) come off from the lcd controller.
3) Firewire - I discarded
4) USB - 4 cables
The iMac has 4 cables as well
3)TMDS - Black
4)TMDS - Gray
Having done both methods, I would recommend using the splicing method. The reason for this is that although there is more soldering, you end up with a surplus of wires. Thus, if you want to add firewire capability, a touch screen etc. you have that option. Also, it is easy to damage the neck when trying to force the extra wires through. Testing it out: