Hi Tariq
Firstly I would not do it as there are too many things running through it HVAC and security so unless you know what you are doing you could end up paying heaps to Holden to reprogram it all for you.
Secondly if you are only wanting to get at the audio and speaker inputs/outputs etc then those are on the right hand side of the unit not at the back so you don't need to pull the unit out.
To get at the inputs just pop the side panel of the driver foot well off and you will see the plugs on the side of the unit. This plastic panel just pops out then slides down and out from under the dash trim. If you have any problems doing that pull off the V trim piece along the dash just above the steering column to get at the screws that hold the underside of the dash in place. Its pretty easy.
Once you have that panel off you can then also get behind and under the unit if needed to run cables or look for connectors.
If you want to remove the radio front panel (which as I said you don't need to do to access the audio plugs) then simply pull it out and up from the bottom above the ashtray or tray.
If you want to remove the unit itself then you will now see approx 4 screws in the metal panel that need to be removed BUT.....
Before you can pull the unit out you need to remove all the plugs not only from the right hand side of the unit as above but I also remember one or two on the left hand side so you will need to take the passenger side panel out as well to get at those. This panel can be removed with a little careful pulling and bending but sometimes you end up having to take out the glove compartment to get clear access to it.
Once again, I would not recommend doing this or unplugging stuff unless you know exactly what you are playing with.
I had all these panels off to install a backing camera, switching unit and VIM (which connects to a plug behind the glove box), its not hard but it is time consuming so its not something you want to do if you don't have too.
