Edit in JSFiddle

Request.YQLajax = new Class({
    // gets basic info such as country and latitude data
    Extends: Request.JSONP,
    options: {
        log: !true,
        url: 'http://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20html%20where%20url%3D%22{location}%22&format=xml'
    },
    initialize: function(location, options) {
        this.parent(options);
        if (!location)
            return;
            
        this.options.url = this.options.url.substitute({location: encodeURIComponent(location)});
    }
});

// example use to fetch BBC's page
new Request.YQLajax("http://www.bbc.co.uk/", {
    onSuccess: function(data) {
        document.id('result').set('html', data.results);
    }
}).send(); 

<div id="result"></div>