Fitting an aux input button to RCD300 (VW Golf mk5, 2006)

Some RCD300s (there are different versions) may not need the CD changer emulator. I think this may apply to units with silver buttons - the black version like mine needed it.
The below - UK websites, I'm sure similar options are available worldwide.
Aux input switch button: www.ebay.co.uk...
CD changer emulator: www.incarconne...
I would fully recommend in car connections: massively friendly service and fast postage in the UK!
Some other relevant and helpful RUclips videos (I'm sure these guys won't mind me sharing):
Remove mk5 Golf radio:
• DIY Removal of an RCD5...
Routing cabling towards gearbox/input switches via driver side footwell panel:
• AUX Installation RCD-5...
Aware I missed a few points of explanation:
Plugging the CD emulator into the radio itself - there's only one place for it to go in the back of the radio, bottom left slot! More in linked videos above.
----THE EARTH LEAD MUST BE CONNECTED to the radio casing, otherwise you'll get 2 beeps and 'NO CD' readout on the radio unit.------
I went straight ahead and soldered the phono cable to the input button cable. You could probably put a female-female mini jack in the button housing if you wanted to use the 2 phono cable that comes with the CD emulator and avoid soldering. I'd never soldered before and managed to make it work so for people wanting to get into soldering it's definitely manageable!
Green molex = red phono core
Red molex = red phono earth
Black molex = black phono core
White molex = black phono earth