Extend the wp_get_archives output with ‘?post_type=foo’?

I’ve gotten my custom post types to display as it should in date based archives; the structure example.com/year/month/day (and above) works properly as long as it’s extended with ‘?post_type=post_type_name’.

With Bainternets solution I’ve also gotten wp_get_archives to properly list archives based on whether or not they contain my CPT.

The problem is that wp_get_archives still returns the default archive permalinks, like this:

example.com/year/month/day

but as I mentioned earlier, I need:

example.com/year/month/day?post_type=post_type_name

Any suggestions on how to achieve this?