If this is meant to be run only in a mod_perl environment, your best bet is probably to make Drall into a module, with a handler which looks something like:

use Apache::Constants qw(:common DIR_MAGIC_TYPE);
sub handler {
  $r = shift;
  return DECLINED unless $r->content_type eq DIR_MAGIC_TYPE;
  do_stuff();
}
[download]

Documentation on the stages of an Apache request, and hence the uses of the mod_perl hooks into them, can be found in the excellent mod_perl book, which has some chapters available online. Chapter 7 may help with what you are trying to do.

perl -pe '"I lo*`+$^X$\"$]!$/"=~m%(.*)%s;$_=$1;y^`+*^e v^#$&V"+@( NO CARRIER'