timelocal expects a bunch of input parameters, one per date component. It's often rather easy to parse the date yourself, if it has a predefined format, and pull out individual parts. All parameters are numbers, so if you have to parse a month name, you can convert it to a month number using a small Perl data structure. If you parse a month number, be wary that timelocal expects the month number for January is 0. So you may have to subtract 1 to get the correct value.

It's all not too much work, you can usually make it work within a couple of minutes, but if it proves to be too hard for you, you can always fall back to parsing the date using one of the (rather heavy-weight) date parsing modules, that likely can convert it to epoch seconds for you, as well.