I just can't see why this would need coding??
Unless....they code the radio to output a balanced differential output over the speaker wires, which is what the hi-fi head unit does.
Either way, this now makes it a stupid price imho, the Alpine amp is worth around £100 at most, paying £250 for it because it is approved is fair enough, but £300 for the amp, £330 for coding and 2 hours at an average of say £200 is laughable.
That is nearly £900, for that money you could get into some serious hi end sounding gear whilst keeping it completely stock looking.