/usr/src/perl/pod/perlfaq4/How_can_I_take_a_string_and_turn.pod

How can I take a string and turn it into epoch seconds?

If it's a regular enough string that it always has the same format, you can split it up and pass the parts to timelocal in the standard Time::Local module. Otherwise, you should look into one of the Date modules off of CPAN.