Neither does Time::Local, but it didn't stop him from doing his own parsing. Do you really need a module to replace a regex match or

my ($Y,$M,$D, $h,$m,$s) = unpack('A4xA2xA2xA2xA2xA2', $time_str);
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From that, you can contruct a DateTime object and do date and time arithmetic.

That said, I don't see the need to replace Time::Local with DateTime here. It seems to me that L~R made appropriate and maximal use of modules. Now, if you wanted the answer to be of the form X days, Y Hours and Z Seconds, DateTime is your man!