The problem with getting a new radio, is that this functionality isn't always available in the new radio so you have now defunct buttons on your steering wheel.That is, unless, you spend a lot of money on a compatible radio.
I have a Sony xplod CDX-GT110 which does.t have this functionality, but it's bigger brother CDX-GT270 does have this.
In face, many of the stereos, CDX-GT35 CDX-GT130 CDX-GT330 CDX-GT440 all look the same(ish) but do not have this functionality
It seems if you don'y have it, you don't have it.... or do you?
Philips screw driver
Soldering iron and Solder
3.5mm adapter socket
Hook up wire
(RCA plugs for Aux out)
Step 1: Disassemble
Then remove the screws holding the CD player and lift this out of the unit - taking care as it lifts out of the connector.
Remove all the screws from the back heat sink panel and the front panel so you are left with just the board in the bottom chassis.
Remove the silver screws and carefully lift the main board from the metal chassis.
Step 2: Locate the Missing Connector Spaces
This is where you add your desired functionality.
Step 3: Extending the Main Board
Solder some hook up wire to the pads and leave about 15cm length so that it leads outside the chassis when you put it back together again.
Solder the connector so that it connects to the pads on the PCB.
For the stalk adapter, Sony have been particularly sneaky and left some links missing on the board - just in case you tried to solder a connector on and gain functionality - herein is the hack.
Solder a short piece of wire across this gap, thereby connecting the pads that now have the new connector attached - to the processor on the bottom of the board. - your stalk adapter is now connected.
Step 4: Pack Away and Re-install in Your Car.
1-Insert the main board
2-the main board's silver screws
3-the front panel and it's clip
4-the heatsink on the back
6-the top-piece of metal to close the chassis.
Be sure to wrap any exposed connectors in insulating tape so that it does not touch any metal once installed back in the car.
Step 5: Enjoy
I personally have an autoleads PC99 adapter to interface with my astra. I just bought the sony adapter and it works perfectly with my steering wheel controls
I didn't install the aux out (as I have no need) but tested them with a set of powered speakers and it does work. Simply install another 3.5mm adapter to the aux out pads - just like the remote, and use a short 3.5mm to RCA adapter outside the radio,
If you want to install the CD changer/aux in - that may not work because there are some missing components on the board and the firmware in the IC may not be flashed to use them. Maybe it is, I don't know, I'm a teacher not a Sony Engineer.