The quintessence of this problem has been solved in (Golf) Ordered Combinations:

# tilly's combinator
sub c {
  @r='';@r=map{$c=$_;map$c.$_,@r}@_ for 1..shift;@r
}

print join $/, map "#$_", c qw(3 00 33 66 99 CC FF);
[download]

   MeowChow                                   
               s aamecha.s a..a\u$&owag.print