As you may remember, Apple officially discontinued the LCD cable needed for this upgrade, so you can't find it through certified reseller or repair channels any longer. You may be able to find the cable on eBay, or you can solder the wires from the original cable directly to the pins on the LCD connection of the XGA Samsung LCD.
I remember that someone did this when the project originally got underway, but I can't remember who it is - if that person still reads this community, please feel free to post some photos of the work you did, so that others can use it for the project. I can host photos if necessary.
Thanks!