unpack and POSIX's strftime can do the trick.

use POSIX qw( strftime );
my ($y,$m,$d) = unpack( 'A4 A2 A2', '20100302165019' );
print( uc( strftime( "%d-%b-%y", 0,0,0, $d,$m-1,$y ) ), "\n" );
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Well, %b isn't guaranteed to return the months in English, so you might want to create a lookup table instead of using strftime.

my @months = qw( JAN FEB MAR ... DEC );
my ($y,$m,$d) = unpack( 'A4 A2 A2', '20100302165019' );
print( sprintf( "%02d-%s-%02d", $d, $months[$m-1], $y-2000 ), "\n" );
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print and sprintf can be combined using printf.

Update: Added lookup table solution.

perl -we 'use Date::Manip; print uc UnixDate($ARGV[0], "%d-%b-%y\n");'
+ '20100302165019'
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How about:

use HTTP::Date qw( time2iso str2time );

my $original  = '20100302165019';
my ($year, $month, $day) = $original =~ m{^(\d{4})(\d{2})(\d{2})};
my $time      = str2time("$year\-$month\-$day");
my $localtime = localtime( $time );
my $isodate   = time2iso($time);

print "Localtime: '$localtime'\n";
print "ISO Date: '$isodate'\n";
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Your output would be:

Localtime: 'Tue Mar  2 00:00:00 2010'
ISO Date: '2010-03-02 00:00:00'
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