I have done this in the past numerous times, including convincing the IT department of the investment banking arm of a large German bank to use Perl as the main scripting tool for Unix and NT platforms.

First, if the problems you work about are not important to someone on the business side, you will probably loose. You normally need someone from the business side fighting on your side.

Second, the first thing is to prove that the module you want to use solves the problem. Create a prototype, or a "tracer bullet" if you want to use the code in the future. Do this in a time slice where nobody can say you are wasting your time on useless things.

Third, convince the people that have the business problem that you can solve it. A running demo or prototype usually gets the point across very fast.

Now, go to your boss, pointing out that you have solved an important business problem. Tell him how you did it, and supply the things you need to make a new tool acceptable in your work environment. Usually, this means providing a support address. Easy for Perl. There are several companies that offer support. Provide a reference to those. If any conflicts arise on this level, raise the odds by confronting your boss with the business people. Usually, they don't care about IT internal stuff like Perl modules etc., and will be happy about the solution you demonstrated to them. In the typical company, your boss will lose, since the business is the owner of the money in the end.

Note: using other people's modules does not relieve you from the obligation to understand what they do, and how they do it. A part of point two (prototype) above is investigating if the module really solves your problem. It won't do you any good to propose solutions that break down in the face of real world concerns like security, stability, maintainability, and so on. E.g., if you are the only one that understands the code, then you have a problem anyway.

Christian Lemburg
Brainbench MVP for Perl
http://www.brainbench.com