Thomas,
No matter what the client wants; in this case the best they can do with a Varicam is 4:2:2 color sampling and record the HD-SDI output (spigot on back of camera) into a capture card (like AJA Kona) connected to FCP using ProRes highest quality codec.
The only cameras that provide full 4:4:4 color sampling are F23/35, Viper, Dalsa, Genesis and Arri D21.
In the Varicam class, a superior (1920×1080) and or more convenient 4:2:2 workflow would be to use a Panasonic 3000 and record 10 bit color depth on P2 cards.
I find it amusing that clients throw around technical jargon without knowing what they’re talking about. It would be more appropriate for them to merely ask the camerperson for advice in determining the best possible workflow for quality, and then, as is the usual procedure settle for less because they can’t afford it.
JS