Edit in JSFiddle

var Todo = new Class({
    Implements: Chain,
    initialize: function() {
        this.chain.apply(this, arguments);
        this.callChain();
    }
});

var myTodoList = new Todo(
    function() {
        $('log').grab(new Element('p[text=get groceries]'));
        this.callChain.delay(500, this);
    }, function() {
        $('log').grab(new Element('p[text=go workout]').fade('in'));
        this.callChain.delay(500, this);
    }, function() {
        $('log').grab(new Element('p[text=code mootools documentation until eyes close involuntarily]').fade('in'));
        this.callChain.delay(500, this);
    }, function() {
        $('log').grab(new Element('p[text=sleep]'));
    }
);

<div id="log"></div>