If you have the environment set up for offline coding, which is explained at http://mathandcode.com/blog2/2012/09/running-khan-academy-javascript-code-offline/, you could just copy and paste the code.

Patrick, the link you published is no longer valid.

Thanks Pablo.

Other instructions can be found at http://www.petercollingridge.co.uk/blog/running-khan-academy-programs-your-computer and advanced instructions at http://processingjs.org/articles/jsQuickStart.html