I hope many of you have seen this amazing video made by Bret Victor: Inventing on Principle. This is one of the best introduction to live coding if you never heard about it.
Recently, Code Orchestra, released an amazing tool named COLT. It enables live coding in AS3, you will find many great video examples on their page. You can use the tool with a free trial during 15 days, don’t hesitate! It comes with many examples to help you understand the basis, oh and there is one running with the Citrus Engine 😉