Bottom line: you can't. At some point the script must always be parser (and human) readable for mIRC to parse it. There's no way to do it short of putting your scripts inside DLL's which is just plain ridiculous and inefficient. Not to mention the fact that if people can't see your code it strongly makes it look like you have something to hide.

What it comes down to is: have you really scripted something so amazing that it's not been done a dozen times before? And if so why not let people see the code so maybe they can learn from it?

Spelling mistakes, grammatical errors, and stupid comments are intentional.