Release your code under some kind of license (Recommend GPLv2 or GPLv3 for least restrictions or just state explicitly that User assumes all responsibility for use with no copy/re-use/distribution restrictions)
Declare all your dependencies at the beginning of your script. Besides Perl, whatever is used for the actual conversion.
GPL is full of restrictions. It was created exactly to restrict what you can (or can not) do. If you want the least restrictive license, use something like BSD or MIT.