It's still not entirely clear to me what you are looking for -- your restated question seems ambiguous because you say "5 seconds between them" is what you are looking for, however, Date::Manip returning a number of seconds between two dates is insufficient.

At any rate, Date::Manip (does not require compilation) appears to cover all of the contingencies in your problem. From the Date::Manip docs:

  4.  The amount of time between two dates.

      $date1=&ParseDate($string1);
      $date2=&ParseDate($string2);
      $delta=&DateCalc($date1,$date2,\$err);
          => 0:0:WK:DD:HH:MM:SS   the weeks, days, hours, minutes,
                                  and seconds between the two
      $delta=&DateCalc($date1,$date2,\$err,1);
          => YY:MM:WK:DD:HH:MM:SS  the years, months, etc. between
                                   the two
[download]

In the interests of being specific, how exactly is this not meeting your needs?

Cheers,
Matt