How about something simple ..

if ( /^:object_dir=\.\./ )
{
  my $vob = "bllblbl";
  my $baseDir = "koko";

  my @Data = split ( /\// );
  print "$Data[0]/$vob/$baseDir/$Data[1]\n";
}
else
{
  print;
}
[download]

This code isn't tested.

--t. alex
but my friends call me T.