Hi Alex,
If you want to learn the 'older' style sling I think I still have a pdf book (out of print). You tube videos are also helpful. Expect (at first) to suck, and be a danger to everything around you.
Remember that you have to practice with full force at all times. When I first started I was easily launching errant stones the length of a football field (in almost every direction...not so far behind me).
IF you can figure out how to send me a private message with your email I can try to hunt down the book.
-NIM