Copy a script form a website to another one.

Hello everyone, here's what I'm looking for. There's a website that has a script to generate keys based on certain information you input. It is free, they don't charge anything but I use it about 10-15 times a day and sometimes I have to use it on a computer with no internet connection. So what I need it's someone that extract the necessary files and scripts to recreate that very same function to an offline site. I want to get rid off everything else that has nothing to do the function itself, and of course the result has to work just like the original website. I'm not involved with that website in anyway and I have no access to the files. So please let me know if that can be done. Thanks.