I have been investigating the code of template-functions-general.php and I believe I would need to change this line:
echo '<a href="' . get_day_link($thisyear, $thismonth, $day) . "" title="$ak_titles_for_day[$day]">$day</a>";
Get_day_link should be replaced with something like the_permalink, but that doesn’t work outside of The Loop. get_permalink doesn’t work either, as it displays the same permalink for all calendar entries.
Any ideas??