It's pretty hard-coded as it is now... the function being used is PHP's number_format(), which, taking only one argument, formats it wil a comma:
http://www.php.net/manual/en/function.number-format.php
So, either
a) go through the code changing this function,
b) create a custom layer with preg_replace() on things like $this->content['ranking']['items'][]
c) ask nicely for the points format to be more flexible in a later release.