Squeezebox show custom content (no iframe)

Question

I'd like to show some custom (HTML) content on a squeezebox (within Joomla). To show an iFrame I'm using this code:

window.addEvent('domready', function() {
    SqueezeBox.open('https://whatever.com', {handler: 'iframe'});
});

Thats working fine. But how can I display whatever I want?!