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
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)
You may find 5K0 907 044 AK ZJU versions on Ebay in which the only difference is a slight change on heater buttons