For European users, i tried this in postlist.php:
// get what weekday the first is on
$tempDate = getdate(mktime(0,0,0,$mon,1,$year));
$firstwday= $tempDate["wday"]-1; //HACK: Monday starts week instead of Sunday: '-1' added
if ($firstwday==-1) {$firstwday=6;} //HACK: Monday starts week instead of Sunday: first day should not be -1
And here: (update the header namings...)
<tr class="tdheader"><th>Montag</th><th>Dienstag</th><th>Mittwoch</th><th>Donnerstag</th><th>Freitag</th><th>Samstag</th><th>Sonntag</th></tr>