well there is a ton of videos on line showing how to do the work itself. but with the ST 2, you will have to do it at the amp itself, for the front woofer channels. also if you are doing this to add an amp for speakers instead of subs, then you need to add load resistors to keep the OEM amp from burning itself up, and really you should just be getting a DSR1 instead. but also if you are adding this to add an amp for subwoofers, then you should look into a LOC that offers bass restoration like an AudioControl unit since the OEM system rolls the bass off the more you turn up the volume.
no something I have to ask since I dont know how much of your car is different from US model cars... I dont see a Sony badge on your radio, do your cars still have an aftermarket amp in the back under the cover? this may be different than what we need to do.