You need Dual Zone Climate control in the car already. If you don't have this then it is too costly to do.
Then you need this panel
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Which is from the Passat CC. You may also need a new Central Elec Control Module BUT i'm fairly certain everything needed is contained within the panel.
I know of a couple of people who have done this but it has been in Octavia's. One of those panels was on eBay recently for £160
Part no. is 5K0 907 044 BD ZJU which is for a Satin Black one. From a dealer they are around the £300 mark.
You may also need a new Can-Gateway depending on your car as the earliest anyone i know to have this working is at least an S revision
You will also need a new MFD3 Surround or you could do this (which incidentally is on a MK5 2007 Golf)
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You may find 5K0 907 044 AK ZJU versions on Ebay in which the only difference is a slight change on heater buttons
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