The DBD::Interbase::FAQ perldoc has a section on "How can I use the date/time formatting attributes?" To summarize, you can specify the format as an attribute when preparing the statement.

my $sth = $dbh->prepare( $query, { ib_timeformat => '%e.%m.%G %H:%M:%S
+' } )
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should get you pretty close to what you want; experiment with the format string as you wish. (I've done plenty of DBI coding, but haven't used DBD::Interbase yet.)