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.