[Vince]

Just read the license, really. It states what you can and can't do with the script. If there isn't a license then the script is inherently copyrighted by the original owner and in that case you don't have permission to modify it in any way. This is why it's important to include a proper license with each release; MIT is a good license, as is the MPL. GPL is ultrabad because it's not compatible with any other license and it forces you to make all your code open source, even if you don't want to.