I take it this code was written by someone (not yourself) within the Koha community. And as your post stands, it would probably be accurate to assert that you haven't gained a good understanding of the code, or possibly even of programming with Perl. But you're not really asking a Perl question, or any question, for that matter. It seems that you're requesting that someone do the work of adding a feature to an existing project so that it will better fit your needs. It might be more effective to raise an issue with the project's developers requesting the feature, and maybe offering to contribute your support either in technical capital, or if you're not a programmer and don't intend to learn to be one, the green-paper kind.

I see on the Koha website Get Involved, and Support, which also links to both mailing lists and support companies.

If you're actually trying to work on this yourself and have encountered a technical hurdle to overcome, by all means, explain what's holding you up, what you've tried, and what questions you might need resolved in order to proceed. We're game to help if there's a Perl question in there somewhere. But, speaking for myself, I don't get too excited when presented with a narrowly-specialized need, 400 lines of code, and no sign of the existence of a programmer engaging at the OP end of the conversation.

It's not too late to turn this thread positive. Tell us what you've done to get started. What your level of experience with Perl (and programming in general) is. Tell us where you're stuck. Explain your understanding of the problem and what you see as the challenges. And ask a question.