possible to replace window.location.hash?

Yes, you can. I do something similar at one of my sites, although with href instead of id, but id works too. A quick example:

$('a[id]').click(function(e)
{
    // This will change the URL fragment. The change is reflected
    // on your browser's address bar as well
    window.location.hash = this.id;
    e.preventDefault();
});