This longish article in Wikipedia lays out current thinking regarding pædophilia from a psychiatric point of view:
               Article

To Donuel, most surely, where there is life there is hope. Your elegant prose: "For the throng of society it takes too long for the deranged to change". This is painfully true..."Lock 'em up & throw away the key...chemical castration, etc, etc.. "Today's society demands instant solutions; society must be protected & rightly so.
      
To Joe & Steve, law enforcement & mental health professionals need a protocol that alerts an integrated team. Imprisonment combined with rehabilitation has been the stated aim in the US & UK for a good long time, but the results are very uneven with too many, catastrophic releases, often exacerbated by offenders not taking prescribed medication.

I haven't looked into the research, but I suspect genetics will play an increasingly important rôle.

I have training & experience & anecdotes aplenty... answers have I none, but these measured exchanges are a microcosm of the macrocosmic debate, alluded to by Jim.

I fear the cost of 'getting it right' would be astronomical.