You can try webshims, which is available on cdn + only loads the polyfill, if it is needed.
Here is a demo with CDN:
http://jsfiddle.net/trixta/BMEc9/
<!-- cdn for modernizr, if you haven't included it already -->
<script src="http://cdn.jsdelivr.net/webshim/1.12.4/extras/modernizr-custom.js"></script>
<!-- polyfiller file to detect and load polyfills -->
<script src="http://cdn.jsdelivr.net/webshim/1.12.4/polyfiller.js"></script>
<script>
webshims.setOptions('waitReady', false);
webshims.setOptions('forms-ext', {types: 'date'});
webshims.polyfill('forms forms-ext');
</script>
<input type="date" />
In case the default configuration does not satisfy, there are many ways to configure it. Here you find the datepicker configurator.
Note: While there might be new bugfix releases for webshim in the future. There won’t be any major releases anymore. This includes support for jQuery 3.0 or any new features.