The best way to install is using Bower.
$ bower install adt-nette-ajax --save
Link file with desired extensions in your templates (usually in app/@layout.latte, after nette.ajax.js).
Runs your callback multiple times. First immediatelly and then before/after/complete each nette.ajax snippet processing. In $el variable is either $(document) (in case of first immediate call) or snippet. Callback is not run immediatelly in case of before, because it does not make sense.
You should use only $el.find('#my-element') to address HTML nodes in given snippet (or in document in case of first immediate call). Do not use general query $('#my-element') if you don't really know what you are doing.
$.nette.ext('live').after(function($el){ ... });
$.nette.ext('live').before(function($el){ ... });
$.nette.ext('live').complete(function($el){ ... });