Once the elements to be sorted have been combined into a single string it is just a lexical sort so you can use a simple anonymous routine to reverse the order.

knoppix@Microknoppix:~$ perl -E '
> @dates = qw{
>    10/02/2004
>    02/01/2004
>    01/02/2004
>    01/06/2004
>    01/02/2005
>    01/12/2004
>    08/18/2010
>    };
> say for
>    map  { substr $_, 8 }
>    sort { $b cmp $a }
>    map  { join q{}, ( split m{/} )[ 2, 0, 1 ], $_ }
>    @dates;'
08/18/2010
01/02/2005
10/02/2004
02/01/2004
01/12/2004
01/06/2004
01/02/2004
knoppix@Microknoppix:~$
[download]