package MyOrder;
use strict;
# export junk goes here...

my %order = (
# order hash goes here...
);

sub SortMyWay {  
  if ( exists $order{$a} and exists $order{$b} ) {
    return $order{$a} <=> $order{$b}
  } elsif ( exists $order{$a} ) {
    return 1
  } elsif ( exists $order{$b} ) { 
    return -1 
  } else { 
    return $a cmp $b 
  } 
} 

package main;
use strict;
# use the module with the sort stuff in it, 
# which also exports sub SortMyWay

my @foo = (
# stuff to sort goes here...
);

my @bar = sort SortMyWay @foo;