Hi there,
If you're still watching this thread,
It depends on what kind of learner you are.
I, personally, learned at least half (probably more), of what I know by looking at scripts. I changed some, and see what happened.
There's lots of tutorials, some for beginners as well.
I've always loved
http://www.javascriptkit.com/, but I don't know if there are any beginner tutorials there. Also, this site focuses on Javascript used in Webpages, so it may not be your best bet if you plan on creating Msg Plus Live scripts.
It might help to know basic XML (or maybe even HTML at the least, you can copy past), to create interface windows and to create the info file.
The links that Menthix gave you are also a great place to look for info. I use them when I'm unsure about something.
I hope you enjoy learning scripting!
P.S. If you can find any of my scripts, I give you my full permission to edit them and see what happens when you start learning.