My approach to this is to wrap the button with a link in order to use jquery ui css without creating a link.
To access the button, you will need to assign an identifier to it in the initial parameters.
$('#your-selector').dialog({
resizable: false,
height: 260,
closeOnEscape: true,
width: 475,
modal: true,
.....
buttons: [
{
text: "Continue Shopping",
id: "continue-d-btn",
click: function () { $(this).dialog("close"); }
},
{
text: "Checkout",
id: "checkout-d-btn"
}
],
open: function (event, ui) {
$('#checkout-d-btn')
.wrap('<a href="[YOUR_LINK]" ></a>');
}
});