Yes possible. Done that.
Relatively simple except, if you have a fresh air flap done with two motors. That will never work properly. If you only have one motor (MY2008 onwards usually) then that part is not a problem either. Flap housing can be changed to single motor one but sourcing the flap housing will be a problem. I had to buy the complete unit that is installed inside dashboard just to get the housing. Also the swap was really tedious without removing all the dashboard stuff around it. But can be done without dismantling it completely. Just needs a little patience and small hands
Also new radio/clima facia is needed but can be found easily from
ebay.
Some wiring changes involved as well. But very simple to do.
More info here :
http://forums.vwvortex.com/showthre...-on-a-MKV-on-a-RNS-510-Screen-installed/page3
BUT, you won't be able to make it work completely error free without also upgrading the cluster to white or color cluster. It will raise a function restricted due to missing message error in climatronic as it won't be able to communicate properly with comfort bus devices. I did not see any changes in how the climatronic works but the error comes all the time.
After I upgraded to color MFD it went away.
Also if you want to have all the features the swap provides, you need to have a radio that supports the new climatronic as well. Means RCD510, RNS510, RN315 or RN310 or similar.
Oh and you are talking about mk5 climatronic to mk6 climatronic? Climatic (semi-automatic) conversion is not possible to do.